def __init__(
self,
atoms,
timestep,
temperature,
externalstress,
ttime,
pfactor,
mask=None,
trajectory=None,
logfile=None,
loginterval=1,
):
MolecularDynamics.__init__(self, atoms, timestep, trajectory, logfile, loginterval)
# self.atoms = atoms
# self.timestep = timestep
self.zero_center_of_mass_momentum(verbose=1)
self.temperature = temperature
self.set_stress(externalstress)
self.set_mask(mask)
self.eta = zeros((3, 3), float)
self.zeta = 0.0
self.zeta_integrated = 0.0
self.initialized = 0
self.ttime = ttime
self.pfactor_given = pfactor
self._calculateconstants()
self.timeelapsed = 0.0
self.frac_traceless = 1
def __init__(self, atoms, timestep=0.1*units.fs,
logfile=None, trajectory=None,
loginterval=1, offset=(0.1, 0, 0)):
MolecularDynamics.__init__(self, atoms, timestep,
logfile, trajectory,
loginterval)
self._offset = np.array(offset)
def __init__(self, atoms, timestep, temperature, friction, fixcm=True,
trajectory=None, logfile=None, loginterval=1,
communicator=world):
MolecularDynamics.__init__(self, atoms, timestep, trajectory,
logfile, loginterval)
self.temp = temperature
self.frict = friction
self.fixcm = fixcm # will the center of mass be held fixed?
self.communicator = communicator
self.updatevars()
def __init__(self, atoms, timestep, temperature, taut, fixcm=True,
trajectory=None, logfile=None, loginterval=1,
communicator=world):
MolecularDynamics.__init__(self, atoms, timestep, trajectory,
logfile, loginterval)
self.taut = taut
self.temperature = temperature
self.fixcm = fixcm # will the center of mass be held fixed?
self.communicator = communicator
def attach(self, function, interval=1, *args, **kwargs):
"""Attach callback function or trajectory.
At every *interval* steps, call *function* with arguments
*args* and keyword arguments *kwargs*.
If *function* is a trajectory object, its write() method is
attached, but if *function* is a BundleTrajectory (or another
trajectory supporting set_extra_data(), said method is first
used to instruct the trajectory to also save internal
data from the NPT dynamics object.
"""
if hasattr(function, "set_extra_data"):
# We are attaching a BundleTrajectory or similar
function.set_extra_data("npt_init", WeakMethodWrapper(self, "get_init_data"), once=True)
function.set_extra_data("npt_dynamics", WeakMethodWrapper(self, "get_data"))
MolecularDynamics.attach(self, function, interval, *args, **kwargs)
def __init__(self, atoms, dt, trajectory=None, logfile=None,
loginterval=1):
MolecularDynamics.__init__(self, atoms, dt, trajectory, logfile,
loginterval)
if not atoms.has('momenta'):
atoms.set_momenta(np.zeros((len(atoms), 3), float))
self.calculator = atoms.get_calculator()
self.asap_md = asap3._asap.VelocityVerlet(atoms, self.calculator, dt)
# Identify FixAtoms constraint
if atoms.constraints:
assert len(atoms.constraints) == 1
constraint = atoms.constraints[0]
assert isinstance(constraint, asap3.constraints.FixAtoms)
constraint.prepare_for_asap(atoms)
mask = constraint.index
assert mask.shape == (len(atoms),) and mask.dtype == bool
mult = np.logical_not(mask).astype(float)
self.atoms.arrays["FixAtoms_mult_double"] = mult
def attach_atoms(self, atoms):
"""Assign atoms to a restored dynamics object.
This function must be called to set the atoms immediately after the
dynamics object has been read from a trajectory.
"""
try:
self.atoms
except AttributeError:
pass
else:
raise RuntimeError("Cannot call attach_atoms on a dynamics "
"which already has atoms.")
MolecularDynamics.__init__(self, atoms, self.dt)
limit = 1e-6
h = self._getbox()
if max(abs((h - self.h).ravel())) > limit:
raise RuntimeError("The unit cell of the atoms does not match the unit cell stored in the file.")
self.inv_h = linalg.inv(self.h)
#self._make_special_q_arrays()
self.q = np.dot(self.atoms.get_positions(), self.inv_h) - 0.5
self._calculate_q_past_and_future()
self.initialized = 1
def __init__(self,
atoms,
timestep,
temperature,
ttime,
trajectory=None,
logfile=None,
loginterval=1,
**kwargs):
MolecularDynamics.__init__(self, atoms, timestep, trajectory, logfile,
loginterval)
# Initialize simulation parameters
# Q is chosen to be 6 N kT
self.dt = timestep
self.Natom = atoms.get_number_of_atoms()
self.T = temperature
self.targeEkin = 0.5 * (3.0 * self.Natom) * self.T
self.ttime = ttime # * units.fs
self.Q = 3.0 * self.Natom * self.T * (self.ttime * self.dt)**2
self.zeta = 0.0
def attach_atoms(self, atoms):
"""Assign atoms to a restored dynamics object.
This function must be called to set the atoms immediately after the
dynamics object has been read from a trajectory.
"""
try:
self.atoms
except AttributeError:
pass
else:
raise RuntimeError("Cannot call attach_atoms on a dynamics which already has atoms.")
MolecularDynamics.__init__(self, atoms, self.dt)
####self.atoms = atoms
limit = 1e-6
h = self._getbox()
if max(abs((h - self.h).ravel())) > limit:
raise RuntimeError("The unit cell of the atoms does not match the unit cell stored in the file.")
self.inv_h = linalg.inv(self.h)
#self._make_special_q_arrays()
self.q = dot(self.atoms.get_positions(), self.inv_h) - 0.5
self._calculate_q_past_and_future()
self.initialized = 1
def __init__(self, atoms,
timestep, temperature, externalstress, ttime, pfactor,
mask=None, trajectory=None, logfile=None, loginterval=1,
append_trajectory=False):
MolecularDynamics.__init__(self, atoms, timestep, trajectory,
logfile, loginterval,
append_trajectory=append_trajectory)
# self.atoms = atoms
# self.timestep = timestep
self.zero_center_of_mass_momentum(verbose=1)
self.temperature = temperature
self.set_stress(externalstress)
self.set_mask(mask)
self.eta = np.zeros((3, 3), float)
self.zeta = 0.0
self.zeta_integrated = 0.0
self.initialized = 0
self.ttime = ttime
self.pfactor_given = pfactor
self._calculateconstants()
self.timeelapsed = 0.0
self.frac_traceless = 1
def __init__(self,
atoms,
timestep=None,
trajectory=None,
logfile=None,
loginterval=1,
dt=None,
append_trajectory=False):
# FloK: rename dt -> timestep and make sure nobody is affected
if dt is not None:
import warnings
warnings.warn('dt variable is deprecated; please use timestep.',
DeprecationWarning)
timestep = dt
if timestep is None:
raise TypeError('Missing timestep argument')
MolecularDynamics.__init__(self,
atoms,
timestep,
trajectory,
logfile,
loginterval,
append_trajectory=append_trajectory)
def __init__(self, atoms, dt, trajectory=None, logfile=None,
loginterval=1):
MolecularDynamics.__init__(self, atoms, dt, trajectory, logfile,
loginterval)
def __init__(self,
atoms,
timestep,
temperature=None,
externalstress=None,
ttime=None,
pfactor=None,
*,
temperature_K=None,
mask=None,
trajectory=None,
logfile=None,
loginterval=1,
append_trajectory=False):
'''Constant pressure/stress and temperature dynamics.
Combined Nose-Hoover and Parrinello-Rahman dynamics, creating an
NPT (or N,stress,T) ensemble.
The method is the one proposed by Melchionna et al. [1] and later
modified by Melchionna [2]. The differential equations are integrated
using a centered difference method [3]. See also NPTdynamics.tex
The dynamics object is called with the following parameters:
atoms: Atoms object
The list of atoms.
timestep: float
The timestep in units matching eV, Å, u.
temperature: float (deprecated)
The desired temperature in eV.
temperature_K: float
The desired temperature in K.
externalstress: float or nparray
The external stress in eV/A^3. Either a symmetric
3x3 tensor, a 6-vector representing the same, or a
scalar representing the pressure. Note that the
stress is positive in tension whereas the pressure is
positive in compression: giving a scalar p is
equivalent to giving the tensor (-p, -p, -p, 0, 0, 0).
ttime: float
Characteristic timescale of the thermostat, in ASE internal units
Set to None to disable the thermostat.
pfactor: float
A constant in the barostat differential equation. If
a characteristic barostat timescale of ptime is
desired, set pfactor to ptime^2 * B (where ptime is in units matching
eV, Å, u; and B is the Bulk Modulus, given in eV/Å^3).
Set to None to disable the barostat.
Typical metallic bulk moduli are of the order of
100 GPa or 0.6 eV/A^3.
mask: None or 3-tuple or 3x3 nparray (optional)
Optional argument. A tuple of three integers (0 or 1),
indicating if the system can change size along the
three Cartesian axes. Set to (1,1,1) or None to allow
a fully flexible computational box. Set to (1,1,0)
to disallow elongations along the z-axis etc.
mask may also be specified as a symmetric 3x3 array
indicating which strain values may change.
Useful parameter values:
* The same timestep can be used as in Verlet dynamics, i.e. 5 fs is fine
for bulk copper.
* The ttime and pfactor are quite critical[4], too small values may
cause instabilites and/or wrong fluctuations in T / p. Too
large values cause an oscillation which is slow to die. Good
values for the characteristic times seem to be 25 fs for ttime,
and 75 fs for ptime (used to calculate pfactor), at least for
bulk copper with 15000-200000 atoms. But this is not well
tested, it is IMPORTANT to monitor the temperature and
stress/pressure fluctuations.
References:
1) S. Melchionna, G. Ciccotti and B. L. Holian, Molecular
Physics 78, p. 533 (1993).
2) S. Melchionna, Physical
Review E 61, p. 6165 (2000).
3) B. L. Holian, A. J. De Groot, W. G. Hoover, and C. G. Hoover,
Physical Review A 41, p. 4552 (1990).
4) F. D. Di Tolla and M. Ronchetti, Physical
Review E 48, p. 1726 (1993).
'''
MolecularDynamics.__init__(self,
atoms,
timestep,
trajectory,
logfile,
loginterval,
append_trajectory=append_trajectory)
# self.atoms = atoms
# self.timestep = timestep
if externalstress is None:
raise TypeError("Missing 'externalstress' argument.")
if ttime is None:
raise TypeError("Missing 'ttime' argument.")
if pfactor is None:
raise TypeError("Missing 'pfactor' argument.")
self.zero_center_of_mass_momentum(verbose=1)
self.temperature = units.kB * self._process_temperature(
temperature, temperature_K, 'eV')
self.set_stress(externalstress)
self.set_mask(mask)
self.eta = np.zeros((3, 3), float)
self.zeta = 0.0
self.zeta_integrated = 0.0
self.initialized = 0
self.ttime = ttime
self.pfactor_given = pfactor
self._calculateconstants()
self.timeelapsed = 0.0
self.frac_traceless = 1
def __init__(self,
atoms,
timestep,
temperature=None,
friction=None,
fixcm=True,
*,
temperature_K=None,
trajectory=None,
logfile=None,
loginterval=1,
communicator=world,
rng=None,
append_trajectory=False):
"""
Parameters:
atoms: Atoms object
The list of atoms.
timestep: float
The time step in ASE time units.
temperature: float (deprecated)
The desired temperature, in electron volt.
temperature_K: float
The desired temperature, in Kelvin.
friction: float
A friction coefficient, typically 1e-4 to 1e-2.
fixcm: bool (optional)
If True, the position and momentum of the center of mass is
kept unperturbed. Default: True.
rng: RNG object (optional)
Random number generator, by default numpy.random. Must have a
standard_normal method matching the signature of
numpy.random.standard_normal.
logfile: file object or str (optional)
If *logfile* is a string, a file with that name will be opened.
Use '-' for stdout.
trajectory: Trajectory object or str (optional)
Attach trajectory object. If *trajectory* is a string a
Trajectory will be constructed. Use *None* (the default) for no
trajectory.
communicator: MPI communicator (optional)
Communicator used to distribute random numbers to all tasks.
Default: ase.parallel.world. Set to None to disable communication.
append_trajectory: boolean (optional)
Defaults to False, which causes the trajectory file to be
overwriten each time the dynamics is restarted from scratch.
If True, the new structures are appended to the trajectory
file instead.
The temperature and friction are normally scalars, but in principle one
quantity per atom could be specified by giving an array.
RATTLE constraints can be used with these propagators, see:
E. V.-Eijnden, and G. Ciccotti, Chem. Phys. Lett. 429, 310 (2006)
The propagator is Equation 23 (Eq. 39 if RATTLE constraints are used)
of the above reference. That reference also contains another
propagator in Eq. 21/34; but that propagator is not quasi-symplectic
and gives a systematic offset in the temperature at large time steps.
"""
if friction is None:
raise TypeError("Missing 'friction' argument.")
self.fr = friction
self.temp = units.kB * self._process_temperature(
temperature, temperature_K, 'eV')
self.fixcm = fixcm # will the center of mass be held fixed?
self.communicator = communicator
if rng is None:
self.rng = np.random
else:
self.rng = rng
MolecularDynamics.__init__(self,
atoms,
timestep,
trajectory,
logfile,
loginterval,
append_trajectory=append_trajectory)
self.updatevars()
def __init__(self,
atoms,
timestep,
temperature,
lattice_friction,
simulation_number,
fixcm=True,
trajectory=None,
logfile=None,
loginterval=1,
communicator=world,
rng=np.random):
""" The number of POSCAR file with initial conditions, also how many lattice atoms are frozen"""
self.simulation_number = str(simulation_number)
self.frozen_lattice = 8.
""" How often should the height of molecules be checked, on what height to freeze """
self.freeze_interval = 50
self.freeze_height = 17.0
self.freeze_counter = 0
""" Load timestep and C and O masses in atomic units"""
self.timestep = timestep
self.C_mass = 12.
self.O_mass = 16.
""" Read temperatures from T_el_ph.dat into 1D arrays and generate interpolated functions"""
temperature_file = np.loadtxt(temperature)
temp_t = temperature_file[:, 0] * units.fs
temp_el = temperature_file[:, 1] * units.kB
temp_ph = temperature_file[:, 2] * units.kB
self.interpolated_el_temp = interpolate.interp1d(temp_t,
temp_el,
kind='cubic')
self.interpolated_ph_temp = interpolate.interp1d(temp_t,
temp_ph,
kind='cubic')
""" Parameters for fitted density function """
self.a = 0.203631
self.b = 2.43572093
self.c = 1.71554638
self.d = 3.7611108
self.cutoff = 100.
"""Make empty arrays for the coefficients """ # find journal reference
self.natoms = atoms.get_number_of_atoms()
self.c1 = self.c2 = self.c3 = self.c4 = self.c5 = np.zeros(self.natoms)
""" Get indices of adsorbate and surface atoms """
self.symbols = np.asarray(atoms.get_chemical_symbols(), dtype=str)
self.C_indices = np.flatnonzero(self.symbols == 'C')
self.O_indices = np.flatnonzero(self.symbols == 'O')
self.lattice_indices = np.flatnonzero(self.symbols == 'Pd')
self.adsorbate_indices = np.concatenate(
(self.C_indices, self.O_indices))
self.adsorbate_number = len(self.adsorbate_indices)
self.lattice_number = len(self.lattice_indices)
""" Make empty arrays for atom temperatures and atom frictions. """
self.T = np.zeros(self.natoms)
self.friction = np.zeros(self.natoms)
""" Set friction for surface atoms immediately since it is constant during the simulation """
np.put(self.friction, self.lattice_indices, lattice_friction)
""" Get atomic masses """
self.mass = atoms.get_masses()
""" Friction conversion factor from a.u. to ase units """
self.conversion_factor = 0.02267902937 / units.fs
self.fixcm = fixcm # will the center of mass be held fixed?
self.communicator = communicator
self.rng = rng
MolecularDynamics.__init__(self, atoms, timestep, trajectory, logfile,
loginterval)
self.updatevars()
def __init__(self,
atoms,
timestep,
temperature=None,
taut=None,
fixcm=True,
*,
temperature_K=None,
trajectory=None,
logfile=None,
loginterval=1,
communicator=world,
append_trajectory=False):
"""Berendsen (constant N, V, T) molecular dynamics.
Parameters:
atoms: Atoms object
The list of atoms.
timestep: float
The time step in ASE time units.
temperature: float
The desired temperature, in Kelvin.
temperature_K: float
Alias for *temperature*
taut: float
Time constant for Berendsen temperature coupling in ASE
time units.
fixcm: bool (optional)
If True, the position and momentum of the center of mass is
kept unperturbed. Default: True.
trajectory: Trajectory object or str (optional)
Attach trajectory object. If *trajectory* is a string a
Trajectory will be constructed. Use *None* for no
trajectory.
logfile: file object or str (optional)
If *logfile* is a string, a file with that name will be opened.
Use '-' for stdout.
loginterval: int (optional)
Only write a log line for every *loginterval* time steps.
Default: 1
append_trajectory: boolean (optional)
Defaults to False, which causes the trajectory file to be
overwriten each time the dynamics is restarted from scratch.
If True, the new structures are appended to the trajectory
file instead.
"""
MolecularDynamics.__init__(self,
atoms,
timestep,
trajectory,
logfile,
loginterval,
append_trajectory=append_trajectory)
if taut is None:
raise TypeError("Missing 'taut' argument.")
self.taut = taut
self.temperature = self._process_temperature(temperature,
temperature_K, 'K')
self.fix_com = fixcm # will the center of mass be held fixed?
self.communicator = communicator
def __init__(self,
atoms,
timestep,
temperature_K,
andersen_prob,
fixcm=True,
trajectory=None,
logfile=None,
loginterval=1,
communicator=world,
rng=random,
append_trajectory=False):
""""
Parameters:
atoms: Atoms object
The list of atoms.
timestep: float
The time step in ASE time units.
temperature_K: float
The desired temperature, in Kelvin.
andersen_prob: float
A random collision probability, typically 1e-4 to 1e-1.
With this probability atoms get assigned random velocity components.
fixcm: bool (optional)
If True, the position and momentum of the center of mass is
kept unperturbed. Default: True.
rng: RNG object (optional)
Random number generator, by default numpy.random. Must have a
random_sample method matching the signature of
numpy.random.random_sample.
logfile: file object or str (optional)
If *logfile* is a string, a file with that name will be opened.
Use '-' for stdout.
trajectory: Trajectory object or str (optional)
Attach trajectory object. If *trajectory* is a string a
Trajectory will be constructed. Use *None* (the default) for no
trajectory.
communicator: MPI communicator (optional)
Communicator used to distribute random numbers to all tasks.
Default: ase.parallel.world. Set to None to disable communication.
append_trajectory: bool (optional)
Defaults to False, which causes the trajectory file to be
overwritten each time the dynamics is restarted from scratch.
If True, the new structures are appended to the trajectory
file instead.
The temperature is imposed by stochastic collisions with a heat bath
that acts on velocity components of randomly chosen particles.
The algorithm randomly decorrelates velocities, so dynamical properties
like diffusion or viscosity cannot be properly measured.
H. C. Andersen, J. Chem. Phys. 72 (4), 2384–2393 (1980)
"""
self.temp = units.kB * temperature_K
self.andersen_prob = andersen_prob
self.fix_com = fixcm
self.rng = rng
if communicator is None:
communicator = DummyMPI()
self.communicator = communicator
MolecularDynamics.__init__(self,
atoms,
timestep,
trajectory,
logfile,
loginterval,
append_trajectory=append_trajectory)
def todict(self):
d = MolecularDynamics.todict(self)
d.update({'temperature': self.temp,
'friction': self.fr,
'fix-cm': self.fixcm})
return d
def todict(self):
d = MolecularDynamics.todict(self)
d.update({'temperature_K': self.temp / units.kB,
'friction': self.fr,
'fixcm': self.fix_com})
return d
def __init__(self, atoms, dt, trajectory=None, logfile=None,
loginterval=1):
MolecularDynamics.__init__(self, atoms, dt, trajectory, logfile,
loginterval)
def todict(self):
d = MolecularDynamics.todict(self)
d.update({'temperature': self.temp,
'friction': self.fr,
'fix-cm': self.fixcm})
return d