what is the energy reference of eigenvalues and potential?

[cpp6f]

I have a few questions about various energies in the OUTCAR file.

1) to what energy are the eigenvalues in the OUTCAR file referenced (i.e. what is the G=0 FFT component of the effective local potential used in the KS equation)? Is this the same reference used for the potential in the LOCPOT file?

2) what is the physical meaning of the alpha+bet correction?

3) is the sum of alpha z and the ewald energy equal to the electrostatic contribution (ignoring correlation and exchange) to the cohesive energy of the ions (treated as point charges) in a compensating uniform electron gas?

Thanks.

[admin]

1) the energies written in OUTCAR are the Kohn-Sham eigenvalues, they are not referenced to any energy level
2) alpha+bet is a rough estimation of the energy offset (V_0) term.