[QE-users] Lattice parameters at finite temperature

[Kazume NISHIDATE]

Dear Jahid Hasan

I don't use cp.x and the following are just general notes for users.
In the Parrinello-Rahman method, we can define a fictional "temperature" for the cell. Refer to equation (3) in the article [1]. The third term on the right-hand side corresponds to the kinetic energy of the cell. As a result, we can determine the "cell temperature." You can also control it using an appropriate temperature control method. The cell temperature is not a true measure of temperature, but can be adjusted to reach a stable state gradually.


 [1] M. Parrinello and A. Rahman, Phys. Rev. Lett. 45 (1980) 1196.

> 2024/06/09 6:10、Md. Jahid Hasan Sagor <md.sagor at maine.edu>のメール:
> 
> Hi,
> 
> To extract lattice parameters of Si/GaAs at finite temperature, we can apply NPT (vc-cp) using CPMD. My question is, do we have to set the desired finite temperature at both of &ION and &CELL card? 
> 
> To me, Only  set temperature  under &ION card should be enough, as I am thinking only ion is the physical quantities. Do you have other opinions for this?
> 
> I tried NPT for Silicon and after 60000 steps, I have found that CELL temperature is not converging at the set temperature under &CELL card, but &ION temperature converged within 3000 steps.
> 
> Please advise me if I am wrong.
> 
> Thank you
> 
> Best
> Md Jahid Hasan
> PhD Student
> Mechanical Engineering
> University of Maine 
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西館数芽
Kazume NISHIDATE Ph.D

Department of Systems Innovation Engineering,
Graduate School of Science and Engineering, Iwate University
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kazume.nishidate at gmail.com, nisidate at iwate-u.ac.jp
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