ASE on your local PC (Cu-Ag-Au)

2025 June 16

The files used in this tutorial can be downloaded from CrySPY_utility/examples/ase_Cu-Ag-Au_EA-vc. This tutorial demonstrates a test run on a local machine using ASE’s lightweight Pure Python EMT calculator. The target system is the ternary Cu-Ag-Au system.

cryspy.in

Example of cryspy.in.

[basic]
algo = EA-vc
calc_code = ASE
nstage = 1
njob = 5
jobcmd = zsh
jobfile = job_cryspy

[structure]
atype = Cu Ag Au
ll_nat = 0 0 0
ul_nat = 8 8 8

[ASE]
ase_python = ase_in.py

[EA]
n_pop = 20
n_crsov = 5
n_perm = 2
n_strain = 2
n_rand = 2
n_add = 3
n_elim = 3
n_subs = 3
target = random
n_elite = 2
n_fittest = 10
slct_func = TNM
t_size = 2
end_point = 0.0 0.0 0.0
maxgen_ea = 0

[option]

Use algo = EA-vc.
When using a bash environment, set jobcmd to bash.
In the [structure] section, use ll_nat to specify the minimum number of atoms for each element, and ul_nat for the maximum.
n_pop = n_crsov + n_perm + n_strain + n_rand + n_add + n_elim + n_subs
The end_point field should be set to the energy per atom (eV/atom) for each pure element—Cu, Ag, and Au. When using ASE’s Pure Python EMT calculator, the energies of the pure elements are zero, so enter 0.0 in each case. (For an example using CHGNet, refer to ASE-CHGNet（Cu-Au）.)
For the parameters in the [EA] section, refer to CrySPY > Input file > [EA] Section and CrySPY > Search algorithms > Variable-composition evolutionary algorithm (EA-vc).
Refer also to CrySPY > Tutorial > Variable-composition evolutionary algorithm (EA-VC) > Analysis and Visualization for the parameters of the automatically generated convex hull plot.

calc_in/

The contents under calc_in/ are the same as those in Tutorial > Random Search (RS) > ASE on your local PC.

calc_in/ase_in.py_1

from ase.constraints import FixSymmetry
from ase.filters import FrechetCellFilter
from ase.calculators.emt import EMT
from ase.optimize import BFGS
import numpy as np
from ase.io import read, write

# ---------- input structure
# CrySPY outputs 'POSCAR' as an input file in work/xxxxxx directory
atoms = read('POSCAR', format='vasp')

# ---------- setting and run
atoms.calc = EMT()
atoms.set_constraint([FixSymmetry(atoms)])
cell_filter = FrechetCellFilter(atoms, hydrostatic_strain=False)
opt = BFGS(cell_filter)
opt.run(fmax=0.01, steps=2000)

# ---------- opt. structure and energy
# [rule in ASE interface]
# output file for energy: 'log.tote' in eV/cell
#                         CrySPY reads the last line of 'log.tote'
# output file for structure: 'CONTCAR' in vasp format
e = cell_filter.atoms.get_total_energy()
with open('log.tote', mode='w') as f:
    f.write(str(e))

# ------ write structure
opt_atoms = cell_filter.atoms.copy()
opt_atoms.set_constraint(None)    # remove constraint for pymatgen
write('CONTCAR', opt_atoms, format='vasp', direct=True)

calc_in/job_cryspy

#!/bin/sh

# ---------- ASE
python3 ase_in.py > out.log

# ---------- CrySPY
sed -i -e '3 s/^.*$/done/' stat_job