[gmx-users] Pressure coupling doubt

[Mark Abraham]

On 29/03/2012 5:38 PM, bipin singh wrote:
> Hello,
>
> I have two doubts regarding pressure coupling in Gromacs:
>
> 1) When I use pcoupl=no
>
> the mdp.out shows the following
>
> ; Pressure coupling
> pcoupl                   = no
> Pcoupltype               = Isotropic
> nstpcouple               = -1
> ; Time constant (ps), compressibility (1/bar) and reference P (bar)
> tau-p                    = 1
> compressibility          =
> ref-p                    =
>
> I have not used the pcoupl(=no) then why it is showing Pcoupltype=Isotropic.

... because that was either the value you input, or the default value. 
Neither matters, because you said not to use pressure coupling.

>
>
> (2) This is a silly question: What will happen if we use following
> option in mdp of NVT simulation:
>
>   pcoupl=no
>   compressibility= 4.5e-5
>
> does it will affect the NVT criteria ? or It will ignore the
> compressibility input?

It will ignore it.

Mark