Hi all, There is not much help document about this problem. To be clear, let me raise some simple examples:
1. x-component of force on atom_n is equal to the y-component of force on atom_m, ntcon=? 2. both x- and y-components of forces on the two atoms in 1 are equal, ntcon=? 3. the magnitudes of forces on two atoms are equal, ntcon=? SIESTA does not watch symmetries. The utility TETR can generate symmetry-aware constr.f, but does not include the variable ntcon. Please help me if you are experienced in writing constr.f. Thanks. Haibo
