How to render a system as an ideal gas

[Xu Wang]

Dear CP2K developers and users:

I want to calculate the Helmholtz free energy of a solid by using first principles molecular dynamics simulations. I plan to utilize the ideal gas as the reference system, and carry out thermodynamic integration from the fully interacting solid to the ideal gas state (Dorner et al., 2018, Phys. Rev. Lett; Rang and Kresse, 2019, Phys. Rev. B):

Such calculations can be accomplished by mixing force_evals in CP2K. However, I don't have a clue what settings or keywords should be used to render the system as an ideal gas in first principles molecular dynamics simulations. Could anyone offer suggestions or examples? Thank you in advance!

Sincerely,
Xu

[ice ZQing]

Dear Xu,

I recently came across your post on the CP2K mailing list regarding the calculation of Helmholtz free energy using first-principles molecular dynamics and thermodynamic integration to an ideal gas reference state. I'm currently facing a similar challenge and found your question highly relevant.

May I ask if you have found a solution or received any suggestions (even off-list) since then? I would really appreciate any advice, references, or example inputs you might be willing to share.

Thank you very much for your time and consideration!

Best regards,
ice ZQing