Is it necessary to apply external pressure in the deformation direction?

User discussions
1

GROMACS version: 2022
GROMACS modification: No

Hi All,

When performing deformation in the z-direction with semi-isotropic coupling, should the reference pressure in the z-direction be set to 1.0 or 0.0? I have set the compressibility in the z-direction to 0.

pcoupl = Parrinello-Rahman
pcoupltype = semiisotropic
tau_p = 1.0
ref_p = 1.0 0.0
compressibility = 4.5e-5 0

@MagnusL Could you please comment on this?

Thank you.

2

It doesn’t really matter what pressure you set in a dimension with 0 compressibility. I usually keep ref_p = 1.0 1.0, but ref_p = 1.0 0.0 should work the same.

3

Yes, it is. I tried it myself and obtained the same result in both cases.

Thanks.