{
rvec_sub(mat_x[i][ind_bond1[m]], mat_x[i][ind_bond2[m]], vec1);
rvec_sub(mat_x2_j[ind_bond1[m]], mat_x2_j[ind_bond2[m]], vec2);
{
rvec_sub(mat_x[i][ind_bond1[m]], mat_x[i][ind_bond2[m]], vec1);
rvec_sub(mat_x2_j[ind_bond1[m]], mat_x2_j[ind_bond2[m]], vec2);