[gmx-users] anisotropic pressure coupling

[Justin A. Lemkul]

Shuangxing Dai wrote:
> Hi, all:
>    I was trying to use pcoupl= Parrinello-Rahman, pcouptype=anisotropic 
> to do pressure coupling for anisotropic material (like crystal). It 
> seems that I need six components for compressibility (xx yy zz xy yz 
> xz). How do I get these six components before I do any MD simulation? 

Surely there are published results that you can refer to for these types of 
considerations.

> Also, if the compressibility changes with temperature and pressure, how 
> can we use a fixed value of compressibility to simulate a system that 
> changes from one state to another? Or the compressibility is not so 
> sensitive to temperature and pressure? 

You can change temperature with simulated annealing, but how do you expect to 
modulate the pressure?  There's no way to systematically alter the pressure.  If 
your goal is to alter these factors somehow, then you have a very complicated 
situation, and there is no really easy way to do it.  You may have to do 
different simulations under different conditions using known compressibilities.

>  Anyone has experience in using Parrinello-Rahman? Thanks in advance.

Sure, many people do.  What is it that you want to know about it?

-Justin

> Thanks,
> Shuangxing Dai
> 

-- 
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Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
MILES-IGERT Trainee
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

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