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from __future__ import print_function
import numpy as np
from ase import Atoms
from ase.calculators.emt import EMT
from ase.optimize import BFGS, BFGSLineSearch
from ase.optimize.precon import Exp, PreconLBFGS
positions = [
[5.8324672234339969, 8.5510800490537271, 5.686535793302002 ],
[7.3587688835494625, 5.646353802990923, 6.8378173997818958],
[7.9908510609316235, 5.4456005797117335, 4.5249260246251213],
[9.7103024117445145, 6.4768915365291466, 4.6502022197421278],
[9.5232482249292509, 8.7417754382952051, 4.6747936030744448],
[8.2738330473112036, 7.640248516254645, 6.1624124370797215],
[7.4198265919217921, 9.2882534361810016, 4.3654132356242874],
[6.8506783463494623, 9.2004422130272605, 8.611538688631887 ],
[5.9081131977596133, 5.6951755645279949, 5.4134092632199602],
[9.356736354387575, 9.2718534012646359, 8.491942486888524 ],
[9.0390271264592403, 9.5752757925665453, 6.4771649275571779],
[7.0554382804264533, 7.0016335250680779, 8.418151938177477 ],
[9.4855926945401272, 5.5650406772147694, 6.8445655410690591],
]
atoms = Atoms('Pt13', positions=positions, cell=[15]*3)
maxstep = 0.2
longest_steps = []
labels = ['BFGS', 'BFGSLineSearch', 'PreconLBFGS_Armijo', 'PreconLBFGS_Wolff']
optimizers = [BFGS, BFGSLineSearch, PreconLBFGS, PreconLBFGS]
for i,Optimizer in enumerate(optimizers):
a = atoms.copy()
a.set_calculator(EMT())
kwargs = {'maxstep':maxstep, 'logfile':None}
if 'Precon' in labels[i]:
kwargs['precon'] = Exp(A=3)
kwargs['use_armijo'] = 'Armijo' in labels[i]
opt = Optimizer(a, **kwargs)
opt.run(steps=1)
dr = a.get_positions() - positions
steplengths = (dr**2).sum(1)**0.5
longest_step = np.max(steplengths)
print('%s: longest step = %.4f' % (labels[i], longest_step))
longest_steps.append(longest_step)
longest_steps = np.array(longest_steps)
assert (longest_steps < maxstep + 1e-8).all()
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