Assistance with Calculating Material Properties at Different Temperatures and Pressures Using VASP.

[hszhao.cn@gmail.com]

Dear VASP Community,

I am currently working on a project that involves calculating various material properties at different temperatures and pressures. Specifically, I am interested in determining the following properties of a given material:

1. Specific heat capacity at constant volume (Cv)
2. Specific heat capacity at constant pressure (Cp)
3. Thermal expansion coefficient (α)
4. Debye temperature (θD)

I would like to seek your guidance on the best practices and detailed steps for performing these calculations, especially regarding the accurate calculation of these properties under varying temperatures and pressures. Additionally, any recommendations for scripts or tools to automate these processes more efficiently would be very helpful.

Thank you in advance for your assistance.

Best regards,
Zhao

[hszhao.cn@gmail.com]

See here for the related discussion.

Regards,
Zhao

[henrique_miranda]

I think I cannot add much more to the answer of Atsushi Togo.
Perhaps some other user in this forum can.

I would recommend that you start by the simplest approach, which is using the harmonic and quasi-harmonic approximations, as done in phonopy.
These approximations might deviate from experiments for strongly anharmonic materials at higher temperatures.

You might be able to extract these quantities from molecular dynamics (MD) simulations but there other approximations come into play.
In LAMMPS the quantity of your results will depend on the approximation of the force-field.
Using AIMD as in VASP you might get accurate forces but be limited in the size of your simulation box and integration time unless you combine it with machine learning force-fields.
If you decide to go the MD route, I would still recommend that you compare the results with the harmonic and quasi-harmonic approximation.

[hszhao.cn@gmail.com]

Dear henrique_miranda,

Thank you very much for your comments. I will keep them in mind so that I can adopt a reasonable technical route in future practical comparative studies.

Regards,
Zhao