Category:Meta-GGA: Difference between revisions

Theoretical Background

Meta-GGA exchange-correlation functionals depend on the electron density ${\displaystyle \rho}$, its first derivative ${\displaystyle \nabla\rho}$ and the kinetic-energy density ${\displaystyle \tau}$:

${\displaystyle E_{\mathrm{xc}}^{\mathrm{meta-GGA}}=\int\epsilon_{\mathrm{xc}}^{\mathrm{meta-GGA}}(\rho,\nabla\rho,\tau)d^{3}r}$

Although meta-GGAs are slightly more expensive than GGAs, they are still fast to evaluate and appropriate for very large systems. In general, meta-GGA functionals are more accurate than GGAs. Note that as in most other codes, meta-GGAs are implemented in VASP within the generalized KS scheme^[1]. The meta-GGA that is currently the most widely used in solid-state physics is SCAN^[2]. The meta-GGA functionals using the Laplacian of the electron density, ${\displaystyle \nabla^{2}\rho}$, are not yet available in VASP.

How to

A meta-GGA can be used by specifying the tag METAGGA in the INCAR file.