Esempio n. 1
0
 def __init__(self, lattice, model, chain_list = None, first_structure = None, temperature = 1.0):
     self.lattice = lattice
     self.model = model
     if first_structure is None:
         self.last_structure = random_avoid(self.model.natoms, self.lattice, model = model, chain_list = chain_list)
     else:
         self.last_structure = first_structure
     self.model.calculate_energy(self.last_structure)
     self.best_structure = self.last_structure
     self.best_energy = self.best_structure.energy
     self.mover = Reptate()
     self.step = 0
     if temperature > 0:
         self.rt = float(temperature)
     else:
         raise ValueError("temperature must be > 0")
Esempio n. 2
0
class MonteCarlo(Search):
    '''Perform a Metropolis Monte Carlo search.
    
    Parameters
    ----------
    Required
    lattice: A Lattice frombcga.lattice
    model: A Model from bcga.model
    Optional
    termini: A list containing the indices of the ends of protein chains (only needed for multicain systems)
    first_structure: A bcga.lattice_structure object to start the search (A random one will be generated if none is supplied)
    temperature: The temperature used in the Metropolis test (units are dependent on the model being used)
    '''
    def __init__(self, lattice, model, chain_list = None, first_structure = None, temperature = 1.0):
        self.lattice = lattice
        self.model = model
        if first_structure is None:
            self.last_structure = random_avoid(self.model.natoms, self.lattice, model = model, chain_list = chain_list)
        else:
            self.last_structure = first_structure
        self.model.calculate_energy(self.last_structure)
        self.best_structure = self.last_structure
        self.best_energy = self.best_structure.energy
        self.mover = Reptate()
        self.step = 0
        if temperature > 0:
            self.rt = float(temperature)
        else:
            raise ValueError("temperature must be > 0")
        
    def run(self, steps):
        for self.step in range (self.step +1, self.step + steps + 1):
            structure = self.mover.move(self.last_structure)
            energy = self.model.calculate_energy(structure)
            #print self.step, structure.energy, self.last_structure.energy, self.best_structure.energy
            if structure.energy < self.best_structure.energy:
                self.best_structure = structure
                self.best_energy = energy
            if random.random() < metropolis_probability(self.last_structure.energy, structure.energy, self.rt):
                self.last_structure = structure
        return self.best_structure