### SSNEB with only Z relaxtion?

Posted:

**Fri Nov 27, 2020 1:53 pm**Dear experts,

I would like to know if there some way to fix the supercell lattice parameters in the x and y directions but only to relax in the z direction in the SSNEB method.

I modified the constr_cell_relax.F file as below. This modification works to allow only the z direction relaxation in the normal vasp calculation by using ISIF = 3.

! relaxation in z direction only

SAVE=FCELL(3,3)

FCELL=0 ! F90 style: set the whole array to zero

FCELL(3,3)=SAVE

So I also modified constr_cell_relax.F like above during the compilling 5.3.5 with VTST. However, the output intermediate structures of the SSNEB calculation show that all the lattice parameters in x, y and z directions are changed.

I am wondering it is possible to use SSNEB with only changing the lattice parameter along z direction?

Best wishes,

zhifenh

I would like to know if there some way to fix the supercell lattice parameters in the x and y directions but only to relax in the z direction in the SSNEB method.

I modified the constr_cell_relax.F file as below. This modification works to allow only the z direction relaxation in the normal vasp calculation by using ISIF = 3.

! relaxation in z direction only

SAVE=FCELL(3,3)

FCELL=0 ! F90 style: set the whole array to zero

FCELL(3,3)=SAVE

So I also modified constr_cell_relax.F like above during the compilling 5.3.5 with VTST. However, the output intermediate structures of the SSNEB calculation show that all the lattice parameters in x, y and z directions are changed.

I am wondering it is possible to use SSNEB with only changing the lattice parameter along z direction?

Best wishes,

zhifenh