RPA electron density

[benjamin_shi]

Dear VASP developers,

Is it possible to obtain the electron density (in an AECCAR type file) from an RPA calculation? I'm hoping that it might be possible given that it is possible to compute gradients.

Sincerely,
Benjamin

[jonathan_lahnsteiner2]

Dear Benjamin Shi,

RPA calculations in VASP are performed post-DFT as a many-body correction to the total energy. The RPA method uses the Kohn-Sham orbitals and electron density from a prior (usually PBE or similar) DFT calculation, but it does not generate a new self-consistent electron density or update the density from the RPA method itself. As a result, VASP does not output an electron density file (AECCAR0/AECCAR2 or CHGCAR) for the RPA calculation itself. You can only obtain the electron density corresponding to the underlying DFT (or HF, if used) reference calculation.

Even though gradients (forces, stress) may be computed within RPA, this does not imply that VASP calculates or outputs a new electron density for RPA—a density is strictly defined by the self-consistent field procedure, which RPA does not perform.

I hope this is of help.

All the best Jonathan