ASE on Your Local PC (Cu-Ag-Au)

Last updated: October 16, 2026

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
n_elite = 2
n_fittest = 10
slct_func = TNM
t_size = 2
ref_energies = 0.0 0.0 0.0
maxgen_ea = 0

[option]
rslt_out = always
energy_output_interval = 1
backup_interval = 1

Use algo = EA-vc.
From v1.5.0, energy_output_interval in the [option] section sets the output interval in generations for the convex-hull plot and hull-distance file. Default: 1 (every generation); 0 disables automatic output.
From v1.5.0, backup_interval in the [option] section sets the automatic backup interval in generations. The default is 1; 0 disables automatic backups. See Features > Backup for details.
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 ref_energies (end_point in versions 1.4.3 and earlier) 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

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)

# ---------- run
converged = opt.run(fmax=0.01, steps=2000)

# ---------- rule in ASE interface
# output file for energy: 'log.tote' in eV/cell
#                         CrySPY reads the last line of 'log.tote' file
# outimized structure: 'CONTCAR' file in vasp format
# check_opt: 'out_check_opt' file ('done' or 'not yet')
#                         CrySPY reads the last line of 'out_check_opt' file

# ------ energy
e = cell_filter.atoms.get_total_energy()    # eV/cell
with open('log.tote', mode='w') as f:
    f.write(str(e))

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

# ------ check_opt
with open('out_check_opt', mode='w') as f:
    if converged:
        f.write('done\n')
    else:
        f.write('not yet\n')

calc_in/job_cryspy

#!/bin/sh

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