Damped gradient corrections

Intuitively designed damped gradient corrections have been also used to improve the EDA for correlation. The first attempt of this kind was made by Ma and Brueckner [121] in their paper on the exact second-order expansion of Ec[p]. where they also propose the functional... 

An empirical method to account for dispersive interactions in practical calculations with the density functional theory (termed DFT-D) (Grimme 2006) has been tested for a wide variety of molecular complexes. As in previous schemes, the dispersive energy is described by a damped interatomic potential of the form CeR. The use of pure (non-hybrid), gradient-corrected density functionals (e.g., BLYP or PBE), together with the resolution-of-the-identity... 

Langreth and Mehl [134] used the sharp cut-olf procedure in momentum space to eliminate spurious contributions to and an empirical exponential function to damp the gradient contribution to the energy. The Langreth-Mehl (LM) functional [134,160,161] has now mostly a historical significance. A few years later, Perdew [162] improved the LM functional by imposing two additional requirements that it recover the correct second-order DGE in the slowly varying density limit and reduce in the uniform density limit to LDA, not to the random-phase approximation (RPA), as the LM functional does. Perdew s 1986 correlation functional is... 

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