Clarification on energy/electric enthalpy in Berry phase calculation

[cyrusyc]

Hi,

Is the energy output (e_0_energy) from Berry phase calculation under finite electric field (LCALCPOL = .TRUE.) the electric enthalpy (\(E_0 - \Omega \mathcal{\boldsymbol E} \cdot \mathbf{P}\)) or the system internal energy (first term \(E_0\) on the RHS of electric enthalpy functional in doc https://www.vasp.at/wiki/index.php/Berr ... ric_fields?

Based on doc, VASP minimize the electric enthalpy functional but I didn't see its output. I think it makes more sense if e_0_energy is system's internal energy but would like to confirm.

Thanks,
Yuan

[manuel_engel1]

Hi Yuan,

Thanks for reaching out. In VASP, the \(E_0\) that you see there is the total free energy, which is minimized during the electronic DFT self-consistency cycle. Keep in mind that the total energy calculated by VASP still depends on ISMEAR and SIGMA.

[cyrusyc]

Hi,

Thanks for the reply but it is still not clear to me. Does the e_0_energy contain \(-\Omega \mathbf{E} \cdot \mathbf{P}\) or not?

[manuel_engel1]

No worries. I'm happy to clarify my previous statement. The total energy, which is the e_0_energy that you refer to, does not include the \(-\Omega \mathbf{E} \cdot \mathbf{P}\) term.

Let me know if that answers your question.

[cyrusyc]

Yes. Thanks so much for the clarification!