E0 in OSZICAR

[alexander_duong]

Hello,

Could someone explain what E0 in OSZICAR is? I read in the VASP wiki that it is the energy as sigma approaches zero, but I am not sure what sigma is referring to.

Thanks!

[andreas.singraber]

Hello!

When integrating over k-points often a smearing method is used to improve convergence. The actual method applied in VASP can be selected with the ISMEAR tag. The amount of broadening is controlled with the SIGMA parameter. This is also the sigma value which is taken to zero in order to "recover" what the energy would be without the smearing method. For more details, please have a look at textbooks about density functional theory, e.g.,

• David S. Sholl, Janice A. Steckel: Density Functional Theory: A Practical Introduction

Alternatively, have a look at the original paper for the Methfessel-Paxton method:

• M. Methfessel and A. T. Paxton, Phys. Rev. B 40, 3616, High-precision sampling for Brillouin-zone integration in metals

All the best,
Andreas Singraber

[alexander_duong]

Thank you for the explanation!