What is GGA functional?

A GGA OFKE form is the simplest one-point functional which explicitly includes effects of electron density inhomogeneity. The GGA form, with parameters determined by constraints, has been very successful for approximate XC functionals, to the point that such functionals dominate in practical calculations.

What is meta-GGA?

Meta-GGA (6, 7, 10, 11) is the highest rung at the semilocal level of Jacob’s ladder of DFT, (12) which includes the kinetic energy density as an input in addition to the electron density and its density gradient.

What is hybrid functional in DFT?

Hybrid functionals are a class of approximations to the exchange–correlation energy functional in density functional theory (DFT) that incorporate a portion of exact exchange from Hartree–Fock theory with the rest of the exchange–correlation energy from other sources (ab initio or empirical).

Is GGA a B3LYP?

A hybrid GGA (for example B3LYP) stands for some combination of a standard GGA with a part of Hartree-Fock exchange. A meta-GGA (for example TPSS) has a GGA part, but also depends on the kinetic energy density.

What is the difference between LDA and GGA?

LDA predicts stiffer bonds from which higher values of the IFCs stem; whereas GGA usually gives softer bonds and thus lower values of the IFCs. An alternative approach would be to fix the lattice parameter to the experimental value at the temperature of interest and perform the IFCs calculations as this fixed volume.

What is GGA and PBE?

The generalized gradient approximation (GGA) was used in the scheme of Perdew-Burke-Ernzerhof (PBE) to describe the exchange-correlation functional.

What is GGA approximation?

As the LDA approximates the energy of the true density by the energy of a local constant density, it fails in situations where the density undergoes rapid changes such as in molecules.

What is PBE GGA?

GGA functionals PBE (Perdew et al., 1996) is the default exchange-correlation functional. It is recommended, especially, for studies of molecules interacting with metal surfaces, although it is also fairly reliable for bulk calculations.