示例#1
0
class OTF(object):
    def __init__(self,
                 dft_input: str,
                 dt: float,
                 number_of_steps: int,
                 gp: gp.GaussianProcess,
                 dft_loc: str,
                 std_tolerance_factor: float = 1,
                 prev_pos_init: np.ndarray = None,
                 par: bool = False,
                 skip: int = 0,
                 init_atoms: List[int] = None,
                 calculate_energy=False,
                 output_name='otf_run',
                 max_atoms_added=1,
                 freeze_hyps=10,
                 rescale_steps=[],
                 rescale_temps=[],
                 dft_softwarename="qe",
                 no_cpus=1,
                 npool=None,
                 mpi="srun"):

        self.dft_input = dft_input
        self.dt = dt
        self.number_of_steps = number_of_steps
        self.gp = gp
        self.dft_loc = dft_loc
        self.std_tolerance = std_tolerance_factor
        self.skip = skip
        self.dft_step = True
        self.freeze_hyps = freeze_hyps
        self.dft_module = dft_software[dft_softwarename]

        # parse input file
        positions, species, cell, masses = \
            self.dft_module.parse_dft_input(self.dft_input)

        _, coded_species = struc.get_unique_species(species)

        self.structure = struc.Structure(cell=cell,
                                         species=coded_species,
                                         positions=positions,
                                         mass_dict=masses,
                                         prev_positions=prev_pos_init,
                                         species_labels=species)

        self.noa = self.structure.positions.shape[0]
        self.atom_list = list(range(self.noa))
        self.curr_step = 0

        self.max_atoms_added = max_atoms_added

        # initialize local energies
        if calculate_energy:
            self.local_energies = np.zeros(self.noa)
        else:
            self.local_energies = None

        # set atom list for initial dft run
        if init_atoms is None:
            self.init_atoms = [int(n) for n in range(self.noa)]
        else:
            self.init_atoms = init_atoms

        self.dft_count = 0

        # set pred function
        if not par and not calculate_energy:
            self.pred_func = predict.predict_on_structure
        elif par and not calculate_energy:
            self.pred_func = predict.predict_on_structure_par
        elif not par and calculate_energy:
            self.pred_func = predict.predict_on_structure_en
        elif par and calculate_energy:
            self.pred_func = predict.predict_on_structure_par_en
        self.par = par

        # set rescale attributes
        self.rescale_steps = rescale_steps
        self.rescale_temps = rescale_temps

        self.output = Output(output_name, always_flush=True)

        # set number of cpus and npool for qe runs
        self.no_cpus = no_cpus
        self.npool = npool
        self.mpi = mpi

    def run(self):
        self.output.write_header(self.gp.cutoffs, self.gp.kernel_name,
                                 self.gp.hyps, self.gp.algo, self.dt,
                                 self.number_of_steps, self.structure,
                                 self.std_tolerance)
        counter = 0
        self.start_time = time.time()

        while self.curr_step < self.number_of_steps:
            print('curr_step:', self.curr_step)
            # run DFT and train initial model if first step and DFT is on
            if self.curr_step == 0 and self.std_tolerance != 0:
                # call dft and update positions
                self.run_dft()
                dft_frcs = copy.deepcopy(self.structure.forces)
                new_pos = md.update_positions(self.dt, self.noa,
                                              self.structure)
                self.update_temperature(new_pos)
                self.record_state()

                # make initial gp model and predict forces
                self.update_gp(self.init_atoms, dft_frcs)
                if (self.dft_count - 1) < self.freeze_hyps:
                    self.train_gp()

            # after step 1, try predicting with GP model
            else:
                self.gp.check_L_alpha()
                self.pred_func(self.structure, self.gp, self.no_cpus)
                self.dft_step = False
                new_pos = md.update_positions(self.dt, self.noa,
                                              self.structure)

                # get max uncertainty atoms
                std_in_bound, target_atoms = is_std_in_bound(
                    self.std_tolerance, self.gp.hyps[-1], self.structure,
                    self.max_atoms_added)

                if not std_in_bound:
                    # record GP forces
                    self.update_temperature(new_pos)
                    self.record_state()
                    gp_frcs = copy.deepcopy(self.structure.forces)

                    # run DFT and record forces
                    self.dft_step = True
                    self.run_dft()
                    dft_frcs = copy.deepcopy(self.structure.forces)
                    new_pos = md.update_positions(self.dt, self.noa,
                                                  self.structure)
                    self.update_temperature(new_pos)
                    self.record_state()

                    # compute mae and write to output
                    mae = np.mean(np.abs(gp_frcs - dft_frcs))
                    mac = np.mean(np.abs(dft_frcs))

                    self.output.write_to_log('\nmean absolute error:'
                                             ' %.4f eV/A \n' % mae)
                    self.output.write_to_log('mean absolute dft component:'
                                             ' %.4f eV/A \n' % mac)

                    # add max uncertainty atoms to training set
                    self.update_gp(target_atoms, dft_frcs)
                    if (self.dft_count - 1) < self.freeze_hyps:
                        self.train_gp()

            # write gp forces
            if counter >= self.skip and not self.dft_step:
                self.update_temperature(new_pos)
                self.record_state()
                counter = 0

            counter += 1
            self.update_positions(new_pos)
            self.curr_step += 1

        self.output.conclude_run()

    def run_dft(self):
        self.output.write_to_log('\nCalling DFT...\n')

        # calculate DFT forces
        forces = self.dft_module.run_dft_par(self.dft_input,
                                             self.structure,
                                             self.dft_loc,
                                             no_cpus=self.no_cpus,
                                             npool=self.npool,
                                             mpi=self.mpi)
        self.structure.forces = forces

        # write wall time of DFT calculation
        self.dft_count += 1
        self.output.write_to_log('QE run complete.\n')
        time_curr = time.time() - self.start_time
        self.output.write_to_log('number of DFT calls: %i \n' % self.dft_count)
        self.output.write_to_log('wall time from start: %.2f s \n' % time_curr)

    def update_gp(self, train_atoms, dft_frcs):
        self.output.write_to_log(
            '\nAdding atom {} to the training set.\n'.format(train_atoms))
        self.output.write_to_log('Uncertainty: {}.\n'.format(
            self.structure.stds[train_atoms[0]]))

        # update gp model
        self.gp.update_db(self.structure, dft_frcs, custom_range=train_atoms)

        self.gp.set_L_alpha()

    def train_gp(self):
        self.gp.train(self.output)
        self.output.write_hyps(self.gp.hyp_labels, self.gp.hyps,
                               self.start_time, self.gp.likelihood,
                               self.gp.likelihood_gradient)

    def update_positions(self, new_pos):
        if self.curr_step in self.rescale_steps:
            rescale_ind = self.rescale_steps.index(self.curr_step)
            temp_fac = self.rescale_temps[rescale_ind] / self.temperature
            vel_fac = np.sqrt(temp_fac)
            self.structure.prev_positions = \
                new_pos - self.velocities * self.dt * vel_fac
        else:
            self.structure.prev_positions = self.structure.positions
        self.structure.positions = new_pos
        self.structure.wrap_positions()

    def update_temperature(self, new_pos):
        KE, temperature, velocities = \
                md.calculate_temperature(new_pos, self.structure, self.dt,
                                         self.noa)
        self.KE = KE
        self.temperature = temperature
        self.velocities = velocities

    def record_state(self):
        self.output.write_md_config(self.dt, self.curr_step, self.structure,
                                    self.temperature, self.KE,
                                    self.local_energies, self.start_time,
                                    self.dft_step, self.velocities)
        self.output.write_xyz_config(self.curr_step, self.structure,
                                     self.dft_step)
示例#2
0
文件: otf.py 项目: nw13slx/flare-RC
class OTF(object):
    def __init__(self,
                 qe_input: str,
                 dt: float,
                 number_of_steps: int,
                 gp: gp.GaussianProcess,
                 pw_loc: str,
                 std_tolerance_factor: float = 1,
                 prev_pos_init: np.ndarray = None,
                 par: bool = False,
                 skip: int = 0,
                 init_atoms: List[int] = None,
                 calculate_energy=False,
                 output_name='otf_run',
                 max_atoms_added=1,
                 freeze_hyps=10,
                 rescale_steps=[],
                 rescale_temps=[],
                 no_cpus=1):

        self.qe_input = qe_input
        self.dt = dt
        self.number_of_steps = number_of_steps
        self.gp = gp
        self.pw_loc = pw_loc
        self.std_tolerance = std_tolerance_factor
        self.skip = skip
        self.dft_step = True
        self.freeze_hyps = freeze_hyps

        # parse input file
        positions, species, cell, masses = \
            qe_util.parse_qe_input(self.qe_input)

        _, coded_species = struc.get_unique_species(species)

        self.structure = struc.Structure(cell=cell,
                                         species=coded_species,
                                         positions=positions,
                                         mass_dict=masses,
                                         prev_positions=prev_pos_init,
                                         species_labels=species)

        self.noa = self.structure.positions.shape[0]
        self.atom_list = list(range(self.noa))
        self.curr_step = 0

        self.max_atoms_added = max_atoms_added

        # initialize local energies
        if calculate_energy:
            self.local_energies = np.zeros(self.noa)
        else:
            self.local_energies = None

        # set atom list for initial dft run
        if init_atoms is None:
            self.init_atoms = [int(n) for n in range(self.noa)]
        else:
            self.init_atoms = init_atoms

        self.dft_count = 0

        # set pred function
        if not par and not calculate_energy:
            self.pred_func = self.predict_on_structure
        elif par and not calculate_energy:
            self.pred_func = self.predict_on_structure_par
        elif not par and calculate_energy:
            self.pred_func = self.predict_on_structure_en
        elif par and calculate_energy:
            self.pred_func = self.predict_on_structure_par_en
        self.par = par

        # set rescale attributes
        self.rescale_steps = rescale_steps
        self.rescale_temps = rescale_temps

        self.output = Output(output_name)

        # set number of cpus for qe runs
        self.no_cpus = no_cpus

    def run(self):
        self.output.write_header(self.gp.cutoffs, self.gp.kernel_name,
                                 self.gp.hyps, self.gp.algo, self.dt,
                                 self.number_of_steps, self.structure,
                                 self.std_tolerance)
        counter = 0
        self.start_time = time.time()

        while self.curr_step < self.number_of_steps:
            print('curr_step:', self.curr_step)
            # run DFT and train initial model if first step and DFT is on
            if self.curr_step == 0 and self.std_tolerance != 0:
                # call dft and update positions
                self.run_dft()
                dft_frcs = copy.deepcopy(self.structure.forces)
                new_pos = md.update_positions(self.dt, self.noa,
                                              self.structure)
                self.update_temperature(new_pos)
                self.record_state()

                # make initial gp model and predict forces
                self.update_gp(self.init_atoms, dft_frcs)
                if (self.dft_count - 1) < self.freeze_hyps:
                    self.train_gp()

            # after step 1, try predicting with GP model
            else:
                self.pred_func()
                self.dft_step = False
                new_pos = md.update_positions(self.dt, self.noa,
                                              self.structure)

                # get max uncertainty atoms
                std_in_bound, target_atoms = self.is_std_in_bound()

                if not std_in_bound:
                    # record GP forces
                    self.update_temperature(new_pos)
                    self.record_state()
                    gp_frcs = copy.deepcopy(self.structure.forces)

                    # run DFT and record forces
                    self.dft_step = True
                    self.run_dft()
                    dft_frcs = copy.deepcopy(self.structure.forces)
                    new_pos = md.update_positions(self.dt, self.noa,
                                                  self.structure)
                    self.update_temperature(new_pos)
                    self.record_state()

                    # compute mae and write to output
                    mae = np.mean(np.abs(gp_frcs - dft_frcs))
                    mac = np.mean(np.abs(dft_frcs))

                    self.output.write_to_log('\nmean absolute error:'
                                             ' %.4f eV/A \n' % mae)
                    self.output.write_to_log('mean absolute dft component:'
                                             ' %.4f eV/A \n' % mac)

                    # add max uncertainty atoms to training set
                    self.update_gp(target_atoms, dft_frcs)
                    if (self.dft_count - 1) < self.freeze_hyps:
                        self.train_gp()

            # write gp forces
            if counter >= self.skip and not self.dft_step:
                self.update_temperature(new_pos)
                self.record_state()
                counter = 0

            counter += 1
            self.update_positions(new_pos)
            self.curr_step += 1

        self.output.conclude_run()

    def predict_on_atom(self, atom):
        chemenv = env.AtomicEnvironment(self.structure, atom, self.gp.cutoffs)
        comps = []
        stds = []
        # predict force components and standard deviations
        for i in range(3):
            force, var = self.gp.predict(chemenv, i + 1)
            comps.append(float(force))
            stds.append(np.sqrt(np.abs(var)))

        return comps, stds

    def predict_on_atom_en(self, atom):
        chemenv = env.AtomicEnvironment(self.structure, atom, self.gp.cutoffs)
        comps = []
        stds = []
        # predict force components and standard deviations
        for i in range(3):
            force, var = self.gp.predict(chemenv, i + 1)
            comps.append(float(force))
            stds.append(np.sqrt(np.abs(var)))

        # predict local energy
        local_energy = self.gp.predict_local_energy(chemenv)
        return comps, stds, local_energy

    def predict_on_structure_par(self):
        n = 0
        with concurrent.futures.ProcessPoolExecutor() as executor:
            for res in executor.map(self.predict_on_atom, self.atom_list):
                for i in range(3):
                    self.structure.forces[n][i] = res[0][i]
                    self.structure.stds[n][i] = res[1][i]
                n += 1

    def predict_on_structure_par_en(self):
        n = 0
        with concurrent.futures.ProcessPoolExecutor() as executor:
            for res in executor.map(self.predict_on_atom_en, self.atom_list):
                for i in range(3):
                    self.structure.forces[n][i] = res[0][i]
                    self.structure.stds[n][i] = res[1][i]
                self.local_energies[n] = res[2]
                n += 1

    def predict_on_structure(self):
        for n in range(self.structure.nat):
            chemenv = env.AtomicEnvironment(self.structure, n, self.gp.cutoffs)
            for i in range(3):
                force, var = self.gp.predict(chemenv, i + 1)
                self.structure.forces[n][i] = float(force)
                self.structure.stds[n][i] = np.sqrt(np.abs(var))

    def predict_on_structure_en(self):
        for n in range(self.structure.nat):
            chemenv = env.AtomicEnvironment(self.structure, n, self.gp.cutoffs)
            for i in range(3):
                force, var = self.gp.predict(chemenv, i + 1)
                self.structure.forces[n][i] = float(force)
                self.structure.stds[n][i] = np.sqrt(np.abs(var))
            self.local_energies[n] = self.gp.predict_local_energy(chemenv)

    def run_dft(self):
        self.output.write_to_log('\nCalling Quantum Espresso...\n')

        # calculate DFT forces
        forces = qe_util.run_espresso_par(self.qe_input, self.structure,
                                          self.pw_loc, self.no_cpus)
        self.structure.forces = forces

        # write wall time of DFT calculation
        self.dft_count += 1
        self.output.write_to_log('QE run complete.\n')
        time_curr = time.time() - self.start_time
        self.output.write_to_log('number of DFT calls: %i \n' % self.dft_count)
        self.output.write_to_log('wall time from start: %.2f s \n' % time_curr)

    def update_gp(self, train_atoms, dft_frcs):
        self.output.write_to_log(
            '\nAdding atom {} to the training set.\n'.format(train_atoms))
        self.output.write_to_log('Uncertainty: {}.\n'.format(
            self.structure.stds[train_atoms[0]]))

        # update gp model
        self.gp.update_db(self.structure, dft_frcs, custom_range=train_atoms)

        self.gp.set_L_alpha()

        # if self.curr_step == 0:
        #     self.gp.set_L_alpha()
        # else:
        #     self.gp.update_L_alpha()

    def train_gp(self):
        self.gp.train(self.output)
        self.output.write_hyps(self.gp.hyp_labels, self.gp.hyps,
                               self.start_time, self.gp.like,
                               self.gp.like_grad)

    def is_std_in_bound(self):
        # set uncertainty threshold
        if self.std_tolerance == 0:
            return True, -1
        elif self.std_tolerance > 0:
            threshold = self.std_tolerance * np.abs(self.gp.hyps[-1])
        else:
            threshold = np.abs(self.std_tolerance)

        # sort max stds
        max_stds = np.zeros((self.noa))
        for atom, std in enumerate(self.structure.stds):
            max_stds[atom] = np.max(std)
        stds_sorted = np.argsort(max_stds)
        target_atoms = list(stds_sorted[-self.max_atoms_added:])

        # if above threshold, return atom
        if max_stds[stds_sorted[-1]] > threshold:
            return False, target_atoms
        else:
            return True, [-1]

    def update_positions(self, new_pos):
        if self.curr_step in self.rescale_steps:
            rescale_ind = self.rescale_steps.index(self.curr_step)
            temp_fac = self.rescale_temps[rescale_ind] / self.temperature
            vel_fac = np.sqrt(temp_fac)
            self.structure.prev_positions = \
                new_pos - self.velocities * self.dt * vel_fac
        else:
            self.structure.prev_positions = self.structure.positions
        self.structure.positions = new_pos
        self.structure.wrap_positions()

    def update_temperature(self, new_pos):
        KE, temperature, velocities = \
                md.calculate_temperature(new_pos, self.structure, self.dt,
                                         self.noa)
        self.KE = KE
        self.temperature = temperature
        self.velocities = velocities

    def record_state(self):
        self.output.write_md_config(self.dt, self.curr_step, self.structure,
                                    self.temperature, self.KE,
                                    self.local_energies, self.start_time,
                                    self.dft_step, self.velocities)
        self.output.write_xyz_config(self.curr_step, self.structure,
                                     self.dft_step)
示例#3
0
文件: otf.py 项目: mfhossam1992/flare
class OTF:
    """Trains a Gaussian process force field on the fly during
        molecular dynamics.

    Args:
        dft_input (str): Input file.
        dt (float): MD timestep.
        number_of_steps (int): Number of timesteps in the training
            simulation.
        gp (gp.GaussianProcess): Initial GP model.
        dft_loc (str): Location of DFT executable.
        std_tolerance_factor (float, optional): Threshold that determines
            when DFT is called. Specifies a multiple of the current noise
            hyperparameter. If the epistemic uncertainty on a force
            component exceeds this value, DFT is called. Defaults to 1.
        prev_pos_init ([type], optional): Previous positions. Defaults
            to None.
        par (bool, optional): If True, force predictions are made in
            parallel. Defaults to False.
        skip (int, optional): Number of frames that are skipped when
            dumping to the output file. Defaults to 0.
        init_atoms (List[int], optional): List of atoms from the input
            structure whose local environments and force components are
            used to train the initial GP model. If None is specified, all
            atoms are used to train the initial GP. Defaults to None.
        calculate_energy (bool, optional): If True, the energy of each
            frame is calculated with the GP. Defaults to False.
        output_name (str, optional): Name of the output file. Defaults to
            'otf_run'.
        max_atoms_added (int, optional): Number of atoms added each time
            DFT is called. Defaults to 1.
        freeze_hyps (int, optional): Specifies the number of times the
            hyperparameters of the GP are optimized. After this many
            updates to the GP, the hyperparameters are frozen.
            Defaults to 10.
        rescale_steps (List[int], optional): List of frames for which the
            velocities of the atoms are rescaled. Defaults to [].
        rescale_temps (List[int], optional): List of rescaled temperatures.
            Defaults to [].
        dft_softwarename (str, optional): DFT code used to calculate
            ab initio forces during training. Defaults to "qe".
        no_cpus (int, optional): Number of cpus used during training.
            Defaults to 1.
        npool (int, optional): Number of k-point pools for DFT
            calculations. Defaults to None.
        mpi (str, optional): Determines how mpi is called. Defaults to
            "srun".
        dft_kwargs ([type], optional): Additional arguments which are
            passed when DFT is called; keyword arguments vary based on the
            program (e.g. ESPRESSO vs. VASP). Defaults to None.
        store_dft_output (Tuple[Union[str,List[str]],str], optional):
            After DFT calculations are called, copy the file or files
            specified in the first element of the tuple to a directory
            specified as the second element of the tuple.
            Useful when DFT calculations are expensive and want to be kept
            for later use. The first element of the tuple can either be a
            single file name, or a list of several. Copied files will be
            prepended with the date and time with the format
            'Year.Month.Day:Hour:Minute:Second:'.
    """
    def __init__(self,
                 dft_input: str,
                 dt: float,
                 number_of_steps: int,
                 gp: gp.GaussianProcess,
                 dft_loc: str,
                 std_tolerance_factor: float = 1,
                 prev_pos_init: 'ndarray' = None,
                 par: bool = False,
                 skip: int = 0,
                 init_atoms: List[int] = None,
                 calculate_energy: bool = False,
                 output_name: str = 'otf_run',
                 max_atoms_added: int = 1,
                 freeze_hyps: int = 10,
                 rescale_steps: List[int] = [],
                 rescale_temps: List[int] = [],
                 dft_softwarename: str = "qe",
                 no_cpus: int = 1,
                 npool: int = None,
                 mpi: str = "srun",
                 dft_kwargs=None,
                 store_dft_output: Tuple[Union[str, List[str]], str] = None):

        self.dft_input = dft_input
        self.dt = dt
        self.number_of_steps = number_of_steps
        self.gp = gp
        self.dft_loc = dft_loc
        self.std_tolerance = std_tolerance_factor
        self.skip = skip
        self.dft_step = True
        self.freeze_hyps = freeze_hyps
        self.dft_module = dft_software[dft_softwarename]

        # parse input file
        positions, species, cell, masses = \
            self.dft_module.parse_dft_input(self.dft_input)

        _, coded_species = struc.get_unique_species(species)

        self.structure = struc.Structure(cell=cell,
                                         species=coded_species,
                                         positions=positions,
                                         mass_dict=masses,
                                         prev_positions=prev_pos_init,
                                         species_labels=species)

        self.noa = self.structure.positions.shape[0]
        self.atom_list = list(range(self.noa))
        self.curr_step = 0

        self.max_atoms_added = max_atoms_added

        # initialize local energies
        if calculate_energy:
            self.local_energies = np.zeros(self.noa)
        else:
            self.local_energies = None

        # set atom list for initial dft run
        if init_atoms is None:
            self.init_atoms = [int(n) for n in range(self.noa)]
        else:
            self.init_atoms = init_atoms

        self.dft_count = 0

        # set pred function
        if not par and not calculate_energy:
            self.pred_func = predict.predict_on_structure
        elif par and not calculate_energy:
            self.pred_func = predict.predict_on_structure_par
        elif not par and calculate_energy:
            self.pred_func = predict.predict_on_structure_en
        elif par and calculate_energy:
            self.pred_func = predict.predict_on_structure_par_en
        self.par = par

        # set rescale attributes
        self.rescale_steps = rescale_steps
        self.rescale_temps = rescale_temps

        self.output = Output(output_name, always_flush=True)

        # set number of cpus and npool for DFT runs
        self.no_cpus = no_cpus
        self.npool = npool
        self.mpi = mpi

        self.dft_kwargs = dft_kwargs
        self.store_dft_output = store_dft_output

    def run(self):
        """
        Performs an on-the-fly training run.
        """

        self.output.write_header(self.gp.cutoffs, self.gp.kernel_name,
                                 self.gp.hyps, self.gp.algo, self.dt,
                                 self.number_of_steps, self.structure,
                                 self.std_tolerance)
        counter = 0
        self.start_time = time.time()

        while self.curr_step < self.number_of_steps:
            print('curr_step:', self.curr_step)
            # run DFT and train initial model if first step and DFT is on
            if self.curr_step == 0 and self.std_tolerance != 0:
                # call dft and update positions
                self.run_dft()
                dft_frcs = copy.deepcopy(self.structure.forces)
                new_pos = md.update_positions(self.dt, self.noa,
                                              self.structure)
                self.update_temperature(new_pos)
                self.record_state()

                # make initial gp model and predict forces
                self.update_gp(self.init_atoms, dft_frcs)
                if (self.dft_count - 1) < self.freeze_hyps:
                    self.train_gp()

            # after step 1, try predicting with GP model
            else:
                self.gp.check_L_alpha()
                self.pred_func(self.structure, self.gp, self.no_cpus)
                self.dft_step = False
                new_pos = md.update_positions(self.dt, self.noa,
                                              self.structure)

                # get max uncertainty atoms
                std_in_bound, target_atoms = \
                    is_std_in_bound(self.std_tolerance,
                                    self.gp.hyps[-1], self.structure,
                                    self.max_atoms_added)

                if not std_in_bound:
                    # record GP forces
                    self.update_temperature(new_pos)
                    self.record_state()
                    gp_frcs = copy.deepcopy(self.structure.forces)

                    # run DFT and record forces
                    self.dft_step = True
                    self.run_dft()
                    dft_frcs = copy.deepcopy(self.structure.forces)
                    new_pos = md.update_positions(self.dt, self.noa,
                                                  self.structure)
                    self.update_temperature(new_pos)
                    self.record_state()

                    # compute mae and write to output
                    mae = np.mean(np.abs(gp_frcs - dft_frcs))
                    mac = np.mean(np.abs(dft_frcs))

                    self.output.write_to_log('\nmean absolute error:'
                                             ' %.4f eV/A \n' % mae)
                    self.output.write_to_log('mean absolute dft component:'
                                             ' %.4f eV/A \n' % mac)

                    # add max uncertainty atoms to training set
                    self.update_gp(target_atoms, dft_frcs)
                    if (self.dft_count - 1) < self.freeze_hyps:
                        self.train_gp()

            # write gp forces
            if counter >= self.skip and not self.dft_step:
                self.update_temperature(new_pos)
                self.record_state()
                counter = 0

            counter += 1
            self.update_positions(new_pos)
            self.curr_step += 1

        self.output.conclude_run()

    def run_dft(self):
        """Calculates DFT forces on atoms in the current structure.
        
        If OTF has store_dft_output set, then the specified DFT files will
        be copied with the current date and time prepended in the format
        'Year.Month.Day:Hour:Minute:Second:'.
        """

        self.output.write_to_log('\nCalling DFT...\n')

        # calculate DFT forces
        forces = self.dft_module.run_dft_par(self.dft_input,
                                             self.structure,
                                             self.dft_loc,
                                             ncpus=self.no_cpus,
                                             npool=self.npool,
                                             mpi=self.mpi,
                                             dft_kwargs=self.dft_kwargs)
        self.structure.forces = forces

        # write wall time of DFT calculation
        self.dft_count += 1
        self.output.write_to_log('DFT run complete.\n')
        time_curr = time.time() - self.start_time
        self.output.write_to_log('number of DFT calls: %i \n' % self.dft_count)
        self.output.write_to_log('wall time from start: %.2f s \n' % time_curr)

        # Store DFT outputs in another folder if desired
        # specified in self.store_dft_output
        if self.store_dft_output is not None:
            dest = self.store_dft_output[1]
            target_files = self.store_dft_output[0]
            now = datetime.now()
            dt_string = now.strftime("%Y.%m.%d:%H:%M:%S:")
            if isinstance(target_files, str):
                to_copy = [target_files]
            else:
                to_copy = target_files
            for file in to_copy:
                copyfile(file, dest + '/' + dt_string + file)

    def update_gp(self, train_atoms: List[int], dft_frcs: 'ndarray'):
        """Updates the current GP model.

        Args:
            train_atoms (List[int]): List of atoms whose local environments
                will be added to the training set.
            dft_frcs (np.ndarray): DFT forces on all atoms in the structure.
        """
        self.output.write_to_log(
            '\nAdding atom {} to the training set.\n'.format(train_atoms))
        self.output.write_to_log('Uncertainty: {}.\n'.format(
            self.structure.stds[train_atoms[0]]))

        # update gp model
        self.gp.update_db(self.structure, dft_frcs, custom_range=train_atoms)

        self.gp.set_L_alpha()

    def train_gp(self):
        """Optimizes the hyperparameters of the current GP model."""

        self.gp.train(self.output)
        self.output.write_hyps(self.gp.hyp_labels, self.gp.hyps,
                               self.start_time, self.gp.likelihood,
                               self.gp.likelihood_gradient)

    def update_positions(self, new_pos: 'ndarray'):
        """Performs a Verlet update of the atomic positions.

        Args:
            new_pos (np.ndarray): Positions of atoms in the next MD frame.
        """
        if self.curr_step in self.rescale_steps:
            rescale_ind = self.rescale_steps.index(self.curr_step)
            temp_fac = self.rescale_temps[rescale_ind] / self.temperature
            vel_fac = np.sqrt(temp_fac)
            self.structure.prev_positions = \
                new_pos - self.velocities * self.dt * vel_fac
        else:
            self.structure.prev_positions = self.structure.positions
        self.structure.positions = new_pos
        self.structure.wrap_positions()

    def update_temperature(self, new_pos: 'ndarray'):
        """Updates the instantaneous temperatures of the system.

        Args:
            new_pos (np.ndarray): Positions of atoms in the next MD frame.
        """
        KE, temperature, velocities = \
                md.calculate_temperature(new_pos, self.structure, self.dt,
                                         self.noa)
        self.KE = KE
        self.temperature = temperature
        self.velocities = velocities

    def record_state(self):
        self.output.write_md_config(self.dt, self.curr_step, self.structure,
                                    self.temperature, self.KE,
                                    self.local_energies, self.start_time,
                                    self.dft_step, self.velocities)
        self.output.write_xyz_config(self.curr_step, self.structure,
                                     self.dft_step)
示例#4
0
class MD:
    """Generates NVE dynamics from a GP model."""
    def __init__(self,
                 dt: float,
                 number_of_steps: int,
                 gp: GaussianProcess,
                 pos_init: np.ndarray,
                 species,
                 cell,
                 masses,
                 prev_pos_init: np.ndarray = None,
                 par: bool = False,
                 skip: int = 0,
                 output_name='otf_run.out'):

        self.dt = dt
        self.Nsteps = number_of_steps
        self.gp = gp

        self.structure = Structure(cell=cell,
                                   species=species,
                                   positions=pos_init,
                                   mass_dict=masses,
                                   prev_positions=prev_pos_init)

        self.noa = self.structure.positions.shape[0]
        self.atom_list = list(range(self.noa))
        self.curr_step = 0

        # choose prediction function
        if par is True:
            self.pred_func = predict.predict_on_structure_par_en
        else:
            self.pred_func = predict.predict_on_structure_en

        # initialize local energies
        self.local_energies = np.zeros(self.noa)

        self.pes = []
        self.kes = []

        self.output = Output(output_name)

    def run(self):
        self.output.write_header(self.gp.cutoffs, self.gp.kernel_name,
                                 self.gp.hyps, self.gp.algo, self.dt,
                                 self.Nsteps, self.structure)
        self.start_time = time.time()

        while self.curr_step < self.Nsteps:
            # verlet algorithm follows Frenkel p. 70
            self.gp.check_L_alpha()
            self.pred_func()
            new_pos = md.update_positions(self.dt, self.noa, self.structure)
            self.update_temperature(new_pos)
            self.record_state()
            self.update_positions(new_pos)
            self.curr_step += 1

        self.output.conclude_run()

    def update_positions(self, new_pos):
        self.structure.prev_positions = self.structure.positions
        self.structure.positions = new_pos
        self.structure.wrap_positions()

    def update_temperature(self, new_pos):
        KE, temperature = \
                md.calculate_temperature(new_pos, self.structure, self.dt,
                                         self.noa)
        self.KE = KE
        self.temperature = temperature

    def record_state(self):
        self.pes.append(np.sum(self.local_energies))
        self.kes.append(self.KE)
        self.output.write_md_config(self.dt, self.curr_step, self.structure,
                                    self.temperature, self.KE,
                                    self.local_energies, self.start_time)
        self.output.write_xyz_config(self.curr_step, self.structure,
                                     self.dft_step)
示例#5
0
class MD:
    """Generates NVE dynamics from a GP model."""

    def __init__(self, dt: float, number_of_steps: int, gp: GaussianProcess,
                 pos_init: np.ndarray, species, cell, masses,
                 prev_pos_init: np.ndarray=None, par: bool=False, skip: int=0,
                 output_name='otf_run.out'):

        self.dt = dt
        self.Nsteps = number_of_steps
        self.gp = gp

        self.structure = Structure(cell=cell, species=species,
                                   positions=pos_init,
                                   mass_dict=masses,
                                   prev_positions=prev_pos_init)

        self.noa = self.structure.positions.shape[0]
        self.atom_list = list(range(self.noa))
        self.curr_step = 0

        # choose prediction function
        if par is True:
            self.pred_func = self.predict_on_structure_par_en
        else:
            self.pred_func = self.predict_on_structure_en

        # initialize local energies
        self.local_energies = np.zeros(self.noa)

        self.pes = []
        self.kes = []

        self.output = Output(output_name)

    def run(self):
        self.output.write_header(self.gp.cutoffs, self.gp.kernel_name, self.gp.hyps,
                                 self.gp.algo, self.dt, self.Nsteps, self.structure)
        self.start_time = time.time()

        while self.curr_step < self.Nsteps:
            # verlet algorithm follows Frenkel p. 70
            self.pred_func()
            new_pos = md.update_positions(self.dt, self.noa, self.structure)
            self.update_temperature(new_pos)
            self.record_state()
            self.update_positions(new_pos)
            self.curr_step += 1

        self.output.conclude_run()

    def predict_on_structure_en(self):
        for n in range(self.structure.nat):
            chemenv = AtomicEnvironment(self.structure, n, self.gp.cutoffs)
            for i in range(3):
                force, var = self.gp.predict(chemenv, i + 1)
                self.structure.forces[n][i] = float(force)
                self.structure.stds[n][i] = np.sqrt(np.absolute(var))
            self.local_energies[n] = self.gp.predict_local_energy(chemenv)

    def predict_on_structure_par_en(self):
        n = 0
        with concurrent.futures.ProcessPoolExecutor() as executor:
            for res in executor.map(self.predict_on_atom_en, self.atom_list):
                for i in range(3):
                    self.structure.forces[n][i] = res[0][i]
                    self.structure.stds[n][i] = res[1][i]
                self.local_energies[n] = res[2]
                n += 1
        self.structure.dft_forces = False

    def predict_on_atom_en(self, atom):
        chemenv = AtomicEnvironment(self.structure, atom, self.gp.cutoffs)
        comps = []
        stds = []
        # predict force components and standard deviations
        for i in range(3):
            force, var = self.gp.predict(chemenv, i+1)
            comps.append(float(force))
            stds.append(np.sqrt(np.absolute(var)))

        # predict local energy
        local_energy = self.gp.predict_local_energy(chemenv)
        return comps, stds, local_energy

    def update_positions(self, new_pos):
        self.structure.prev_positions = self.structure.positions
        self.structure.positions = new_pos
        self.structure.wrap_positions()

    def update_temperature(self, new_pos):
        KE, temperature = \
                md.calculate_temperature(new_pos, self.structure, self.dt,
                                         self.noa)
        self.KE = KE
        self.temperature = temperature

    def record_state(self):
        self.pes.append(np.sum(self.local_energies))
        self.kes.append(self.KE)
        self.output.write_md_config(self.dt, self.curr_step, self.structure,
                                    self.temperature, self.KE, self.local_energies,
                                    self.start_time)
        self.output.write_xyz_config(self.curr_step, self.structure,
                                     self.dft_step)
示例#6
0
文件: otf.py 项目: mir-group/flare
class OTF:
    """Trains a Gaussian process force field on the fly during
        molecular dynamics.

    Args:
        dt (float): MD timestep.
        number_of_steps (int): Number of timesteps in the training
            simulation.
        prev_pos_init ([type], optional): Previous positions. Defaults
            to None.
        rescale_steps (List[int], optional): List of frames for which the
            velocities of the atoms are rescaled. Defaults to [].
        rescale_temps (List[int], optional): List of rescaled temperatures.
            Defaults to [].

        gp (gp.GaussianProcess): Initial GP model.
        calculate_energy (bool, optional): If True, the energy of each
            frame is calculated with the GP. Defaults to False.
        calculate_efs (bool, optional): If True, the energy and stress of each
            frame is calculated with the GP. Defaults to False.
        write_model (int, optional): If 0, write never. If 1, write at
            end of run. If 2, write after each training and end of run.
            If 3, write after each time atoms are added and end of run.
            If 4, write after each training and end of run, and back up
            after each write.
        force_only (bool, optional): If True, only use forces for training.
            Default to False, use forces, energy and stress for training.

        std_tolerance_factor (float, optional): Threshold that determines
            when DFT is called. Specifies a multiple of the current noise
            hyperparameter. If the epistemic uncertainty on a force
            component exceeds this value, DFT is called. Defaults to 1.
        skip (int, optional): Number of frames that are skipped when
            dumping to the output file. Defaults to 0.
        init_atoms (List[int], optional): List of atoms from the input
            structure whose local environments and force components are
            used to train the initial GP model. If None is specified, all
            atoms are used to train the initial GP. Defaults to None.
        output_name (str, optional): Name of the output file. Defaults to
            'otf_run'.
        max_atoms_added (int, optional): Number of atoms added each time
            DFT is called. Defaults to 1.
        freeze_hyps (int, optional): Specifies the number of times the
            hyperparameters of the GP are optimized. After this many
            updates to the GP, the hyperparameters are frozen.
            Defaults to 10.
        min_steps_with_model (int, optional): Minimum number of steps the
            model takes in between calls to DFT. Defaults to 0.
        force_source (Union[str, object], optional): DFT code used to calculate
            ab initio forces during training. A custom module can be used here
            in place of the DFT modules available in the FLARE package. The
            module must contain two functions: parse_dft_input, which takes a
            file name (in string format) as input and returns the positions,
            species, cell, and masses of a structure of atoms; and run_dft_par,
            which takes a number of DFT related inputs and returns the forces
            on all atoms.  Defaults to "qe".
        npool (int, optional): Number of k-point pools for DFT
            calculations. Defaults to None.
        mpi (str, optional): Determines how mpi is called. Defaults to
            "srun".
        dft_loc (str): Location of DFT executable.
        dft_input (str): Input file.
        dft_output (str): Output file.
        dft_kwargs ([type], optional): Additional arguments which are
            passed when DFT is called; keyword arguments vary based on the
            program (e.g. ESPRESSO vs. VASP). Defaults to None.
        store_dft_output (Tuple[Union[str,List[str]],str], optional):
            After DFT calculations are called, copy the file or files
            specified in the first element of the tuple to a directory
            specified as the second element of the tuple.
            Useful when DFT calculations are expensive and want to be kept
            for later use. The first element of the tuple can either be a
            single file name, or a list of several. Copied files will be
            prepended with the date and time with the format
            'Year.Month.Day:Hour:Minute:Second:'.

        n_cpus (int, optional): Number of cpus used during training.
            Defaults to 1.
    """
    def __init__(
        self,
        # md args
        dt: float,
        number_of_steps: int,
        prev_pos_init: "ndarray" = None,
        rescale_steps: List[int] = [],
        rescale_temps: List[int] = [],
        # flare args
        gp: gp.GaussianProcess = None,
        calculate_energy: bool = False,
        calculate_efs: bool = False,
        write_model: int = 0,
        force_only: bool = True,
        # otf args
        std_tolerance_factor: float = 1,
        skip: int = 0,
        init_atoms: List[int] = None,
        output_name: str = "otf_run",
        max_atoms_added: int = 1,
        freeze_hyps: int = 10,
        min_steps_with_model: int = 0,
        update_style: str = "add_n",
        update_threshold: float = None,
        # dft args
        force_source: str = "qe",
        npool: int = None,
        mpi: str = "srun",
        dft_loc: str = None,
        dft_input: str = None,
        dft_output="dft.out",
        dft_kwargs=None,
        store_dft_output: Tuple[Union[str, List[str]], str] = None,
        # other args
        n_cpus: int = 1,
        **kwargs,
    ):

        # set DFT
        self.dft_loc = dft_loc
        self.dft_input = dft_input
        self.dft_output = dft_output
        self.dft_step = True
        self.dft_count = 0
        if isinstance(force_source, str):
            self.dft_module = dft_software[force_source]
        else:
            self.dft_module = force_source

        # set md
        self.dt = dt
        self.number_of_steps = number_of_steps
        self.get_structure_from_input(prev_pos_init)  # parse input file
        self.noa = self.structure.positions.shape[0]
        self.rescale_steps = rescale_steps
        self.rescale_temps = rescale_temps

        # set flare
        self.gp = gp
        # initialize local energies
        if calculate_energy:
            self.local_energies = np.zeros(self.noa)
        else:
            self.local_energies = None
        self.force_only = force_only

        # set otf
        self.std_tolerance = std_tolerance_factor
        self.skip = skip
        self.max_atoms_added = max_atoms_added
        self.freeze_hyps = freeze_hyps
        if init_atoms is None:  # set atom list for initial dft run
            self.init_atoms = [int(n) for n in range(self.noa)]
        else:
            self.init_atoms = init_atoms
        self.update_style = update_style
        self.update_threshold = update_threshold

        self.n_cpus = n_cpus  # set number of cpus and npool for DFT runs
        self.npool = npool
        self.mpi = mpi
        self.min_steps_with_model = min_steps_with_model

        self.dft_kwargs = dft_kwargs
        self.store_dft_output = store_dft_output

        # other args
        self.atom_list = list(range(self.noa))
        self.curr_step = 0
        self.last_dft_step = 0

        # Set the prediction function based on user inputs.
        # Force only prediction.
        if (n_cpus > 1 and gp.per_atom_par
                and gp.parallel) and not (calculate_energy or calculate_efs):
            self.pred_func = predict.predict_on_structure_par
        elif not (calculate_energy or calculate_efs):
            self.pred_func = predict.predict_on_structure
        # Energy and force prediction.
        elif (n_cpus > 1 and gp.per_atom_par
              and gp.parallel) and not (calculate_efs):
            self.pred_func = predict.predict_on_structure_par_en
        elif not calculate_efs:
            self.pred_func = predict.predict_on_structure_en
        # Energy, force, and stress prediction.
        elif n_cpus > 1 and gp.per_atom_par and gp.parallel:
            self.pred_func = predict.predict_on_structure_efs_par
        else:
            self.pred_func = predict.predict_on_structure_efs

        # set logger
        self.output = Output(output_name, always_flush=True, print_as_xyz=True)
        self.output_name = output_name
        self.gp_name = self.output_name + "_gp.json"
        self.checkpt_name = self.output_name + "_checkpt.json"
        self.dft_xyz = self.output_name + "_dft.xyz"
        self.checkpt_files = [self.checkpt_name, self.gp_name, self.dft_xyz]

        self.write_model = write_model

    def run(self):
        """
        Performs an on-the-fly training run.

        If OTF has store_dft_output set, then the specified DFT files will
        be copied with the current date and time prepended in the format
        'Year.Month.Day:Hour:Minute:Second:'.
        """

        optional_dict = {"Restart": self.curr_step}
        self.output.write_header(
            str(self.gp),
            self.dt,
            self.number_of_steps,
            self.structure,
            self.std_tolerance,
            optional_dict,
        )

        counter = 0
        self.start_time = time.time()

        while self.curr_step < self.number_of_steps:
            # run DFT and train initial model if first step and DFT is on
            if ((self.curr_step == 0) and (self.std_tolerance != 0)
                    and (len(self.gp.training_data) == 0)):

                # Are the recorded forces from the GP or DFT in ASE OTF?
                # When DFT is called, ASE energy, forces, and stresses should
                # get updated.
                self.initialize_train()

            # after step 1, try predicting with GP model
            else:
                # compute forces and stds with GP
                self.dft_step = False
                self.compute_properties()

                # get max uncertainty atoms
                std_in_bound, target_atoms = is_std_in_bound(
                    self.std_tolerance,
                    self.gp.force_noise,
                    self.structure,
                    max_atoms_added=self.max_atoms_added,
                    update_style=self.update_style,
                    update_threshold=self.update_threshold,
                )

                steps_since_dft = self.curr_step - self.last_dft_step
                if (not std_in_bound) and (steps_since_dft >
                                           self.min_steps_with_model):
                    # record GP forces
                    self.update_temperature()
                    self.record_state()
                    gp_energy = self.structure.potential_energy
                    gp_forces = deepcopy(self.structure.forces)
                    gp_stress = deepcopy(self.structure.stress)

                    # run DFT and record forces
                    self.dft_step = True
                    self.last_dft_step = self.curr_step
                    self.run_dft()
                    dft_frcs = deepcopy(self.structure.forces)
                    dft_stress = deepcopy(self.structure.stress)
                    dft_energy = self.structure.potential_energy

                    # run MD step & record the state
                    self.record_state()

                    # record DFT data into an .xyz file with filename self.dft_xyz.
                    # the file includes the structure, e/f/s labels and atomic
                    # indices of environments added to gp
                    self.record_dft_data(self.structure, target_atoms)

                    # compute mae and write to output
                    self.compute_mae(
                        gp_energy,
                        gp_forces,
                        gp_stress,
                        dft_energy,
                        dft_frcs,
                        dft_stress,
                    )

                    # add max uncertainty atoms to training set
                    self.update_gp(
                        target_atoms,
                        dft_frcs,
                        dft_stress=dft_stress,
                        dft_energy=dft_energy,
                    )

                    if self.write_model == 4:
                        self.checkpoint()
                        self.backup_checkpoint()

            # write gp forces
            if counter >= self.skip and not self.dft_step:
                self.update_temperature()
                self.record_state()
                counter = 0

            counter += 1
            # TODO: Reinstate velocity rescaling.
            self.md_step()  # update positions by Verlet
            self.rescale_temperature(self.structure.positions)

            if self.write_model == 3:
                self.checkpoint()

        self.output.conclude_run()

        if self.write_model >= 1:
            self.write_gp()
            self.checkpoint()

    def get_structure_from_input(self, prev_pos_init):
        positions, species, cell, masses = self.dft_module.parse_dft_input(
            self.dft_input)

        self.structure = struc.Structure(
            cell=cell,
            species=species,
            positions=positions,
            mass_dict=masses,
            prev_positions=prev_pos_init,
            species_labels=species,
        )

    def initialize_train(self):
        # call dft and update positions
        self.run_dft()
        dft_frcs = deepcopy(self.structure.forces)
        dft_stress = deepcopy(self.structure.stress)
        dft_energy = self.structure.potential_energy

        self.update_temperature()
        self.record_state()
        self.record_dft_data(self.structure, self.init_atoms)

        # make initial gp model and predict forces
        self.update_gp(self.init_atoms,
                       dft_frcs,
                       dft_stress=dft_stress,
                       dft_energy=dft_energy)

    def compute_properties(self):
        """
        In ASE-OTF, it will be replaced by subclass method
        """
        self.gp.check_L_alpha()
        self.pred_func(self.structure, self.gp, self.n_cpus)

    def md_step(self):
        """
        Take an MD step. This updates the positions of the structure.
        """
        md.update_positions(self.dt, self.noa, self.structure)
        self.curr_step += 1

    def write_gp(self):
        self.gp.write_model(self.gp_name)

    def run_dft(self):
        """Calculates DFT forces on atoms in the current structure.

        If OTF has store_dft_output set, then the specified DFT files will
        be copied with the current date and time prepended in the format
        'Year.Month.Day:Hour:Minute:Second:'.

        Calculates DFT forces on atoms in the current structure."""

        f = logging.getLogger(self.output.basename + "log")
        f.info("\nCalling DFT...\n")

        # calculate DFT forces
        # TODO: Return stress and energy
        forces = self.dft_module.run_dft_par(
            self.dft_input,
            self.structure,
            self.dft_loc,
            n_cpus=self.n_cpus,
            dft_out=self.dft_output,
            npool=self.npool,
            mpi=self.mpi,
            dft_kwargs=self.dft_kwargs,
        )

        self.structure.forces = forces

        # write wall time of DFT calculation
        self.dft_count += 1
        self.output.conclude_dft(self.dft_count, self.start_time)

        # Store DFT outputs in another folder if desired
        # specified in self.store_dft_output
        if self.store_dft_output is not None:
            dest = self.store_dft_output[1]
            target_files = self.store_dft_output[0]
            now = datetime.now()
            dt_string = now.strftime("%Y.%m.%d:%H:%M:%S:")
            if isinstance(target_files, str):
                to_copy = [target_files]
            else:
                to_copy = target_files
            for ofile in to_copy:
                copyfile(ofile, dest + "/" + dt_string + ofile)

    def update_gp(
        self,
        train_atoms: List[int],
        dft_frcs: "ndarray",
        dft_energy: float = None,
        dft_stress: "ndarray" = None,
    ):
        """
        Updates the current GP model.


        Args:
            train_atoms (List[int]): List of atoms whose local environments
                will be added to the training set.
            dft_frcs (np.ndarray): DFT forces on all atoms in the structure.
        """
        self.output.add_atom_info(train_atoms, self.structure.stds)

        if self.force_only:
            dft_energy = None
            dft_stress = None

        # update gp model
        self.gp.update_db(
            self.structure,
            dft_frcs,
            custom_range=train_atoms,
            energy=dft_energy,
            stress=dft_stress,
        )

        self.gp.set_L_alpha()

        # write model
        if (self.dft_count - 1) < self.freeze_hyps:
            self.train_gp()
            if self.write_model == 2:
                self.write_gp()
        if self.write_model == 3:
            self.write_gp()

    def train_gp(self):
        """Optimizes the hyperparameters of the current GP model."""

        self.gp.train(logger_name=self.output.basename + "hyps")

        hyps, labels = self.gp.hyps_and_labels
        if labels is None:
            labels = self.gp.hyp_labels

        self.output.write_hyps(
            labels,
            hyps,
            self.start_time,
            self.gp.likelihood,
            self.gp.likelihood_gradient,
            hyps_mask=self.gp.hyps_mask,
        )

    def compute_mae(
        self,
        gp_energy,
        gp_forces,
        gp_stress,
        dft_energy,
        dft_forces,
        dft_stress,
    ):

        f = logging.getLogger(self.output.basename + "log")
        f.info("Mean absolute errors & Mean absolute values")

        # compute energy/forces/stress mean absolute error and value
        if not self.force_only:
            e_mae = np.mean(np.abs(dft_energy - gp_energy))
            e_mav = np.mean(np.abs(dft_energy))
            f.info(f"energy mae: {e_mae:.4f} eV")
            f.info(f"energy mav: {e_mav:.4f} eV")

            s_mae = np.mean(np.abs(dft_stress - gp_stress))
            s_mav = np.mean(np.abs(dft_stress))
            f.info(f"stress mae: {s_mae:.4f} eV/A^3")
            f.info(f"stress mav: {s_mav:.4f} eV/A^3")

        f_mae = np.mean(np.abs(dft_forces - gp_forces))
        f_mav = np.mean(np.abs(dft_forces))
        f.info(f"forces mae: {f_mae:.4f} eV/A")
        f.info(f"forces mav: {f_mav:.4f} eV/A")

        # compute the per-species MAE
        unique_species = list(set(self.structure.coded_species))
        per_species_mae = np.zeros(len(unique_species))
        per_species_mav = np.zeros(len(unique_species))
        per_species_num = np.zeros(len(unique_species))
        for a in range(self.structure.nat):
            species_ind = unique_species.index(self.structure.coded_species[a])
            per_species_mae[species_ind] += np.mean(
                np.abs(dft_forces[a] - gp_forces[a]))
            per_species_mav[species_ind] += np.mean(np.abs(dft_forces[a]))
            per_species_num[species_ind] += 1
        per_species_mae /= per_species_num
        per_species_mav /= per_species_num

        for s in range(len(unique_species)):
            curr_species = unique_species[s]
            f.info(
                f"type {curr_species} forces mae: {per_species_mae[s]:.4f} eV/A"
            )
            f.info(
                f"type {curr_species} forces mav: {per_species_mav[s]:.4f} eV/A"
            )

    def rescale_temperature(self, new_pos: "ndarray"):
        """Change the previous positions to update the temperature

        Args:
            new_pos (np.ndarray): Positions of atoms in the next MD frame.
        """
        if self.curr_step in self.rescale_steps:
            rescale_ind = self.rescale_steps.index(self.curr_step)
            temp_fac = self.rescale_temps[rescale_ind] / self.temperature
            vel_fac = np.sqrt(temp_fac)
            self.structure.prev_positions = (
                new_pos - self.velocities * self.dt * vel_fac)

    def update_temperature(self):
        """Updates the instantaneous temperatures of the system.

        Args:
            new_pos (np.ndarray): Positions of atoms in the next MD frame.
        """
        KE, temperature, velocities = md.calculate_temperature(
            self.structure, self.dt, self.noa)
        self.KE = KE
        self.temperature = temperature
        self.velocities = velocities

    def record_state(self):
        self.output.write_md_config(
            self.dt,
            self.curr_step,
            self.structure,
            self.temperature,
            self.KE,
            self.start_time,
            self.dft_step,
            self.velocities,
        )

    def record_dft_data(self, structure, target_atoms):
        # write xyz and energy/forces/stress
        self.output.write_xyz_config(
            self.curr_step,
            self.structure,
            self.structure.forces,
            self.structure.stds,
            dft_forces=self.structure.forces,
            dft_energy=self.structure.potential_energy,
            target_atoms=target_atoms,
        )

    def as_dict(self):
        self.dft_module = self.dft_module.__name__
        out_dict = deepcopy(dict(vars(self)))
        self.dft_module = eval(self.dft_module)

        out_dict["gp"] = self.gp_name
        out_dict["structure"] = self.structure.as_dict()

        for key in ["output", "pred_func"]:
            out_dict.pop(key)

        return out_dict

    @staticmethod
    def from_dict(in_dict):
        if in_dict["write_model"] <= 1:  # TODO: detect GP version
            warnings.warn("The GP model might not be the latest")

        gp_model = gp.GaussianProcess.from_file(in_dict["gp"])
        in_dict["gp"] = gp_model
        in_dict["structure"] = struc.Structure.from_dict(in_dict["structure"])

        if "flare.dft_interface" in in_dict["dft_module"]:
            for dft_name in ["qe", "cp2k", "vasp"]:
                if dft_name in in_dict["dft_module"]:
                    in_dict["force_source"] = dft_name
                    break
        else:  # if force source is a module
            in_dict["force_source"] = eval(in_dict["dft_module"])

        new_otf = OTF(**in_dict)
        new_otf.structure = in_dict["structure"]
        new_otf.dft_count = in_dict["dft_count"]
        new_otf.curr_step = in_dict["curr_step"]
        new_otf.std_tolerance = in_dict["std_tolerance"]
        return new_otf

    def backup_checkpoint(self):
        dir_name = f"{self.output_name}_ckpt_{self.curr_step}"
        os.mkdir(dir_name)
        for f in self.checkpt_files:
            shutil.copyfile(f, f"{dir_name}/{f}")

    def checkpoint(self):
        name = self.checkpt_name
        if ".json" != name[-5:]:
            name += ".json"
        with open(name, "w") as f:
            json.dump(self.as_dict(), f, cls=NumpyEncoder)

    @classmethod
    def from_checkpoint(cls, filename):
        with open(filename, "r") as f:
            otf_model = cls.from_dict(json.loads(f.readline()))

        return otf_model