Example spg_standardize_cell

standardize.c

#include <stdio.h>
#include <stdlib.h>
#include "spglib.h"

static void sub_spg_standardize_cell(double lattice[3][3], double position[][3],
                                     int types[], int const num_atom,
                                     double const symprec,
                                     int const to_primitive,
                                     int const no_idealize) {
    double lat[3][3], pos[4 * 4][3];
    int typ[4 * 4];

    for (int i = 0; i < 3; i++) {
        lat[i][0] = lattice[i][0];
        lat[i][1] = lattice[i][1];
        lat[i][2] = lattice[i][2];
    }

    for (int i = 0; i < num_atom; i++) {
        pos[i][0] = position[i][0];
        pos[i][1] = position[i][1];
        pos[i][2] = position[i][2];
        typ[i] = types[i];
    }

    /* lattice, position, and types are overwritten. */
    int num_primitive_atom = spg_standardize_cell(
        lat, pos, typ, num_atom, to_primitive, no_idealize, symprec);
    printf("VASP POSCAR format: ");
    if (to_primitive == 0) {
        printf("to_primitive=0 and ");
    } else {
        printf("to_primitive=1 and ");
    }

    if (no_idealize == 0) {
        printf("no_idealize=0\n");
    } else {
        printf("no_idealize=1\n");
    }
    printf("1.0\n");
    for (int i = 0; i < 3; i++) {
        printf("%f %f %f\n", lat[0][i], lat[1][i], lat[2][i]);
    }
    printf("%d\n", num_primitive_atom);
    printf("Direct\n");
    for (int i = 0; i < num_primitive_atom; i++) {
        printf("%f %f %f\n", pos[i][0], pos[i][1], pos[i][2]);
    }
}

static void example_spg_standardize_cell_BCC(void) {
    double lattice[3][3] = {{2.51, 0, 0}, {-1.255, 2.17372, 0},{4.09644e-16, 7.09525e-16, 6.69}};

    double position[][3] = {
		{-2.46519e-32, 2.46519e-32, 0.5},
		{0.3333, 0.6667, 0},
		{0, 0, 0},
		{0.6667, 0.3333, 0.5}};

    int types[] = {5, 5, 7, 7};
    int num_atom = 4;
    double symprec = 1e-5;

    /* lattice, position, and types are overwritten. */
    printf("*** Example of spg_standardize_cell (BCC unitcell) ***:\n");
    printf("------------------------------------------------------\n");
    for (int j = 0; j < 2; j++) {
        for (int k = 0; k < 2; k++) {
            sub_spg_standardize_cell(lattice, position, types, num_atom,
                                     symprec, j, k);
            printf("------------------------------------------------------\n");
        }
    }
}


int main(int argc, char* argv[]) {

	printf("%d.%d.%d\n", spg_get_major_version(), spg_get_minor_version(), spg_get_micro_version());
	example_spg_standardize_cell_BCC();
}