Source code for clease.montecarlo.observers.lowest_energy_observer

import logging
import numpy as np
import ase
from clease.datastructures import MCStep
from clease.calculator import CleaseCacheCalculator
from .mc_observer import MCObserver

logger = logging.getLogger(__name__)

[docs]class LowestEnergyStructure(MCObserver): """Track the lowest energy state visited during an MC run. atoms: Atoms object Atoms object used in Monte Carlo track_cf: bool Whether to keep a copy of the correlation functions for the emin structure. If enabled, this will be stored in the ``lowest_energy_cf`` variable. Defaults to False. verbose: bool If `True`, progress messages will be printed """ name = "LowestEnergyStructure" def __init__(self, atoms: ase.Atoms, track_cf: bool = False, verbose: bool = False): super().__init__() self.atoms = atoms self.track_cf = track_cf self.verbose = verbose # Silence pylint self.lowest_energy_cf = None self.reset()
[docs] def reset(self) -> None: self.lowest_energy_cf = None self.emin_atoms: ase.Atoms = self.atoms.copy() # Keep a reference directly to the calculator cache self._calc_cache = CleaseCacheCalculator() self.emin_atoms.calc = self._calc_cache self.lowest_energy = np.inf
@property def lowest_energy(self) -> float: return self.emin_results["energy"] @lowest_energy.setter def lowest_energy(self, value: float) -> None: """The currently best observed energy""" self.emin_results["energy"] = value # Keep a copy without needing to look up the calculator # all the time, for quicker lookup. self._lowest_energy_cache = value @property def emin_results(self) -> dict: """The results dictionary of the lowest energy atoms""" return self._calc_cache.results @property def calc(self): return self.atoms.calc @property def energy(self): """The energy of the current atoms object (not the emin energy)""" return self.calc.results["energy"]
[docs] def observe_step(self, mc_step: MCStep) -> None: """ Check if the current state has lower energy and store the current state if it has a lower energy than the previous state. mc_step: MCStep Instance of MCStep with information on the latest step. """ # We do the comparison even if the move was rejected, # as no energy has been recorded for the first step, yet. # The internal energy cache is np.inf when nothing has been recorded. if < self._lowest_energy_cache: self._update_emin(mc_step) dE = - self.lowest_energy msg = "Found new low energy structure. New energy: %.3f eV. Change: %.3f eV", self.lowest_energy, dE) if self.verbose: print(msg % (self.lowest_energy, dE))
def _update_emin(self, mc_step: MCStep) -> None: if self.track_cf: self.lowest_energy_cf = self.calc.get_cf() self.lowest_energy = # Avoid copying the atoms object multiple times. We can only ever have # changed the symbols, so copy those over from the atoms object. self.emin_atoms.numbers = self.atoms.numbers