Subsections of Evolutionary Algorithm (EA)

ASE on Your Local PC

Last updated: October 16, 2026

The files used in this tutorial can be downloaded from CrySPY_utility/examples/ase_Cu8Au8_EA. This tutorial demonstrates a test run on a local machine using ASE’s lightweight Pure Python EMT calculator. The target system is Cu8Au8.

cryspy.in

Example of cryspy.in.

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

[structure]
atype = Cu Au
nat = 8 8

[EA]
n_pop = 10
n_crsov = 5
n_perm = 2
n_strain = 2
n_rand = 1
n_elite = 1
n_fittest = 5
slct_func = TNM
t_size = 2
maxgen_ea = 0

[ASE]
ase_python = ase_in.py

[option]
rslt_out = always
energy_output_interval = 1
backup_interval = 1
  • Use algo = EA.
  • From v1.5.0, energy_output_interval in the [option] section sets the output interval in generations for the energy plot. 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 EA, tot_struc is not used. The number of structures is determined by n_pop.
  • n_pop = n_crsov + n_perm + n_strain + n_rand
  • For parameters in the [EA] section, refer to Input file > [EA] section and Search algorithms > Evolutionary algorithm (EA).

calc_in/

The contents under calc_in/ are the same as in Tutorial > Random Search (RS) > ASE in 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
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

Create Next Generation

Last updated: October 16, 2026

First Run

When you run cryspy, the program enters structure generation mode. It generates the first generation of random structures and then exits.

cryspy

log

...
[2025-04-06 09:15:34,720][ea_init][INFO] # ---------- Initialize evolutionary algorithm
[2025-04-06 09:15:34,720][ea_init][INFO] # ------ Generation 1
[2025-04-06 09:15:34,720][ea_init][INFO] 10 structures by random

In EA, running cryspy appends the current generation’s information to cryspy.stat.

[status]
generation = 1
id_queueing = 0 1 2 3 4 5 6 7 8 9

Optimize Structures

After running cryspy several times and completing the structure optimization for the first generation, the output will appear as shown below.

...
[2025-04-06 09:20:26,218][ctrl_job][INFO] Done generation 1
[2025-04-06 09:20:26,218][ctrl_job][INFO] 
EA is ready

Create Next Generation

Once all preparations are complete, running cryspy again starts generating the next-generation structures. By default (backup_interval = 1), an automatic backup is performed immediately before generating these structures. From v1.5.0, backup_interval in the [option] section can be used to change the interval in generations; 0 disables automatic backups. See Features > Backup for details.

cryspy
...
[2025-04-06 09:35:11,546][cryspy_restart][INFO] read input, cryspy.in
[2025-04-06 09:35:11,554][ctrl_job][INFO] # ---------- job status
[2025-04-06 09:35:11,554][ctrl_job][INFO] Done generation 1
[2025-04-06 09:35:11,554][utility][INFO] Backup data
[2025-04-06 09:35:11,611][ea_next_gen][INFO] # ---------- Evolutionary algorithm
[2025-04-06 09:35:11,611][ea_next_gen][INFO] Generation 2
[2025-04-06 09:35:11,613][ea_next_gen][INFO] # ------ natural selection
[2025-04-06 09:35:11,687][ea_next_gen][INFO] ranking without duplication (including elite):
[2025-04-06 09:35:11,687][ea_next_gen][INFO] Structure ID      1, fitness:   -0.00530
[2025-04-06 09:35:11,687][ea_next_gen][INFO] Structure ID      3, fitness:    0.01490
[2025-04-06 09:35:11,687][ea_next_gen][INFO] Structure ID      4, fitness:    0.04485
[2025-04-06 09:35:11,687][ea_next_gen][INFO] Structure ID      7, fitness:    0.11501
[2025-04-06 09:35:11,687][ea_next_gen][INFO] Structure ID      8, fitness:    0.15254
[2025-04-06 09:35:11,687][ea_next_gen][INFO] # ------ Generate children
[2025-04-06 09:35:11,687][ea_child][INFO] # -- mindist
[2025-04-06 09:35:11,689][struc_util][INFO] Cu - Cu: 1.32
[2025-04-06 09:35:11,689][struc_util][INFO] Cu - Au: 1.34
[2025-04-06 09:35:11,689][struc_util][INFO] Au - Au: 1.36
[2025-04-06 09:35:11,740][crossover][INFO] Structure ID     10 (8, 8) was generated from      3 and      1 by crossover. Space group:   1 P1
[2025-04-06 09:35:11,764][crossover][WARNING] remove_within_mindist: some atoms within mindist. retry.
[2025-04-06 09:35:11,774][crossover][INFO] Structure ID     11 (8, 8) was generated from      3 and      1 by crossover. Space group:   1 P1
[2025-04-06 09:35:11,789][crossover][INFO] Structure ID     12 (8, 8) was generated from      1 and      4 by crossover. Space group:   1 P1
[2025-04-06 09:35:11,833][crossover][INFO] Structure ID     13 (8, 8) was generated from      1 and      3 by crossover. Space group:   1 P1
[2025-04-06 09:35:11,852][crossover][WARNING] mindist in _add_border_line: Cu - Cu, 0.567032320824818. retry.
[2025-04-06 09:35:11,861][crossover][INFO] Structure ID     14 (8, 8) was generated from      7 and      1 by crossover. Space group:   1 P1
[2025-04-06 09:35:11,875][permutation][INFO] Structure ID     15 (8, 8) was generated from      1 by permutation. Space group: 146 R3
[2025-04-06 09:35:11,888][permutation][INFO] Structure ID     16 (8, 8) was generated from      3 by permutation. Space group:   1 P1
[2025-04-06 09:35:11,890][strain][WARNING] mindist in strain: Cu - Cu, 1.3050485787603692. retry.
[2025-04-06 09:35:11,903][strain][INFO] Structure ID     17 (8, 8) was generated from      3 by strain. Space group:   1 P1
[2025-04-06 09:35:11,917][strain][INFO] Structure ID     18 (8, 8) was generated from      1 by strain. Space group:   1 P1
[2025-04-06 09:35:12,513][ea_child][INFO] # ------ Random structure generation
[2025-04-06 09:35:12,513][rs_gen][INFO] # ------ mindist
[2025-04-06 09:35:12,515][struc_util][INFO] Cu - Cu: 1.32
[2025-04-06 09:35:12,515][struc_util][INFO] Cu - Au: 1.34
[2025-04-06 09:35:12,515][struc_util][INFO] Au - Au: 1.36
[2025-04-06 09:35:12,516][rs_gen][INFO] # ------ generate structures
[2025-04-06 09:35:12,530][gen_pyxtal][INFO] Structure ID     19: (8, 8) Space group:  86 -->  86 P4_2/n
[2025-04-06 09:35:12,533][ea_next_gen][INFO] # ------ Select elites
[2025-04-06 09:35:12,533][ea_next_gen][INFO] Structure ID      9 keeps as the elite

After that, simply running cryspy repeatedly will advance the structure search.

Check Results

Last updated: October 16, 2026

cryspy_rslt

The following is an example of cryspy_rslt after completing calculations up to the third generation. In EA, generation information (Gen) is also included.

From v1.5.0, rslt_out in the [option] section controls when cryspy_rslt and cryspy_rslt_energy_asc are written. The default is always. See Input File > [option] Section for details.

    Gen  Spg_num Spg_sym  Spg_num_opt Spg_sym_opt  E_eV_atom  Magmom      Opt
0     1      214  I4_132          230       Ia-3d   1.168743     NaN  no_file
1     1      198   P2_13          198       P2_13  -0.005303     NaN  no_file
2     1       95  P4_322           95      P4_322   0.389566     NaN  no_file
3     1       27    Pcc2           27        Pcc2   0.014898     NaN  no_file
4     1       60    Pbcn           60        Pbcn   0.044852     NaN  no_file
5     1      116   P-4c2          116       P-4c2   0.403246     NaN  no_file
6     1      187   P-6m2          187       P-6m2   1.054706     NaN  no_file
7     1      161     R3c          160         R3m   0.115009     NaN  no_file
8     1      146      R3          146          R3   0.152535     NaN  no_file
9     1       60    Pbcn           47        Pmmm  -0.005676     NaN  no_file
10    2        1      P1            1          P1   0.026070     NaN  no_file
11    2        1      P1            7          Pc   0.005898     NaN  no_file
12    2        1      P1            1          P1   0.005208     NaN  no_file
13    2        1      P1            1          P1   0.005506     NaN  no_file
14    2        1      P1            1          P1   0.024364     NaN  no_file
15    2      146      R3          146          R3   0.011525     NaN  no_file
16    2        1      P1            1          P1   0.014590     NaN  no_file
17    2        1      P1            1          P1   0.015236     NaN  no_file
18    2        1      P1            2         P-1  -0.012335     NaN  no_file
19    2       86  P4_2/n          140      I4/mcm   0.274548     NaN  no_file
20    3        1      P1            1          P1   0.013611     NaN  no_file
21    3        1      P1           10        P2/m  -0.014166     NaN  no_file
22    3        1      P1            1          P1   0.019472     NaN  no_file
23    3        1      P1            1          P1   0.011641     NaN  no_file
24    3        1      P1            1          P1   0.000297     NaN  no_file
25    3        1      P1            1          P1   0.005596     NaN  no_file
26    3        1      P1            1          P1   0.013374     NaN  no_file
27    3        1      P1            2         P-1   0.005055     NaN  no_file
28    3        2     P-1           12        C2/m  -0.012396     NaN  no_file
29    3      182  P6_322          182      P6_322   0.711472     NaN  no_file

ea_info

The EA parameters used in each generation are recorded in ea_info.

Gen Population Crossover Permutation Strain Random Elite crs_lat slct_func
  1         10         0           0      0     10     0  random       TNM
  2         10         5           2      2      1     1  random       TNM
  3         10         5           2      2      1     1  random       TNM

ea_origin

Information about the structure generation method and parent individuals is output to ea_origin.

Gen Struc_ID   Operation   Parent
  1        0      random     None
  1        1      random     None
  1        2      random     None
  1        3      random     None
  1        4      random     None
  1        5      random     None
  1        6      random     None
  1        7      random     None
  1        8      random     None
  1        9      random     None
  2       10   crossover   (3, 1)
  2       11   crossover   (3, 1)
  2       12   crossover   (1, 4)
  2       13   crossover   (1, 3)
  2       14   crossover   (7, 1)
  2       15 permutation     (1,)
  2       16 permutation     (3,)
  2       17      strain     (3,)
  2       18      strain     (1,)
  2       19      random     None
  2        9       elite    elite
  3       20   crossover (18, 12)
  3       21   crossover  (12, 9)
  3       22   crossover (12, 18)
  3       23   crossover  (18, 9)
  3       24   crossover (13, 18)
  3       25 permutation    (18,)
  3       26 permutation     (9,)
  3       27      strain    (18,)
  3       28      strain    (18,)
  3       29      random     None
  3       18       elite    elite

Analysis and Visualization

Last updated: October 16, 2026

Automatic Energy Plotting

Since version 1.4.4, the energy plot is automatically generated after each generation finishes by default.

The figure is saved to ./data/energy_plot/energy_EA_gen_{gen}.{fig_fotmat}.

From version 1.5.0, the output interval in generations can be changed with energy_output_interval in the [option] section. The default is 1 (every generation); 0 disables automatic output. See Input File > [option] Section for details.

energy_EA_gen_3 energy_EA_gen_3

The following input variables can be set in the [visual] section of cryspy.in. See also CrySPY > Input file > [visual] section.

...
[visual]
ymax = 0.2
markersize = 10
fig_format = svg
...

Replotting with cryspy-Eplot

If you want to fine-tune the figure and replot it, you can easily do so using the cryspy-Eplot command as follows:

cryspy-Eplot

When using the cryspy-Eplot command, the following variables can also be specified in the [visual] section in addition to the standard variables above.

  • plot_min_gen
  • plot_max_gen
  • ref_gen

For example, to replot the figure at generation 2, write the [visual] section as follows:

...
[visual]
plot_max_gen = 2
...

Then, run the following command:

cryspy-Eplot

energy_EA_gen_2 energy_EA_gen_2

In this case, CrySPY overwrites ./data/energy_plot/energy_EA_gen_{gen}.{fig_fotmat}.

You can specify the range of generations to be plotted using plot_min_gen and plot_max_gen. When plot_min_gen is set to specify a range (even if its value is 1), the output is saved with a different filename such as ./data/energy_plot/energy_EA_gen_{plot_min_gen}-{plot_max_gen}.{fig_fotmat}, instead of the usual one. For example, to extract only the results of the second generation from the results available at generation 2:

...
[visual]
plot_min_gen = 2
plot_max_gen = 2
...

energy_EA_gen_2-2 energy_EA_gen_2-2

To change which generation the plot goes up to (i.e., the maximum value of the x-axis), specify the generation with ref_gen. For example, as shown in the image at the top of this page, if three generations have been completed and you want to extract only the results from the second generation, set the [visual] section in cryspy.in as follows:

...
[visual]
plot_max_gen = 2
plot_min_gen = 2
ref_gen = 3
...

If ref_gen is specified, the output filename becomes energy_EA_gen_{plot_min_gen}-{plot_max_gen}_ref_{ref_gen}.{fig_format}.

energy_EA_gen_2-2 energy_EA_gen_2-2

For more advanced data analysis or figure customization, download the files and use Jupyter Notebook as shown below.

Download Data

It is assumed here that you analyze and visualize CrySPY data on your local PC. If you use CrySPY on a supercomputer or workstation, download the data to your local machine. You can delete the work and backup directories if they are not needed, as their file size can be very large.

Jupyter Notebook

Move to the data/ directory in the results you downloaded earlier. Then, if the CrySPY utility has already been downloaded locally, copy cryspy_analyzer_EA.ipynb. Alternatively, you can download it directly from GitHub (CrySPY_utility/notebook/). Launch Jupyter (e.g., VS Code, Jupyter Lab, or Jupyter Notebook), and simply run the cells in order to obtain a figure like the one shown below.

Cu8Au8_EA Cu8Au8_EA