Category:Meta-GGA

Theoretical Background

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

${\displaystyle E_{\mathrm {xc} }^{\mathrm {GGA} }=\int \epsilon _{\mathrm {xc} }^{\mathrm {GGA} }(\rho ,\nabla \rho )d^{3}r}$

Among the various types of functionals, the GGAs are the fastest to evaluate and therefore particularly useful for very large systems. They are very often sufficiently accurate for the geometry optimization or the cohesive energy, but less recommended for properties related to the electronic band structure like the band gap. The GGA that has been the most commonly used in solid-state physics is PBE ^[1].

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