[QE-users] Requested some guidelines in First-principles molecular dynamics

[Lorenzo Paulatto]

I would guess that you calculate the static dielectric constant at the 
temperature-dependent volume (experimental, or quasi-harmonic) and you 
are 90% of the way there. Do you have a specific reason to believe that 
it would be proportional to the RMS ?

Btw, the code d3_r2q.x included with the "anharmonic" package can 
compute the RMS from an inexpensive phonon calculation, maybe have a 
look at it before doing a large supercell MD.

https://anharmonic.github.io/thermal2/#d3_r2qx-code

cheers

On 10/01/2024 19:35, Md. Jahid Hasan Sagor wrote:
> Actually, I have to calculate Dielectric constant for GaAs for 
> different temperatures (not 0 k). To do that, I need to extract atomic 
> positions for different RMS using CPMD. If anyone know someone/ or 
> give some guidelines, it would be great help for me.
>
> Thank you.
>
> On Tue, Jan 9, 2024, 2:09 PM Md. Jahid Hasan Sagor 
> <md.sagor at maine.edu> wrote:
>
>     Dear QE community,
>
>     I want to calculate the mean square displacement of GaAs using
>     CPMD. From the mean square displacement, I want to extract the
>     configuration of atoms (e.g atomic position of Ga and As). Could
>     anyone please give me some guidelines on how I can perform it?
>     Should I use only the cp.x package or by other means? Your time
>     and suggestions would be a great help for me.
>
>     Best Regards
>     Md Jahid Hasan
>     PhD Student, Mechanical Engineering
>     University of Maine
>
>
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-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC - CNRS UMR 7590 & Sorbonne Université
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