1301.3225 (O. Anatole von Lilienfeld)

Force correcting atom centered potentials for generalized gradient
approximated density functional theory: Approaching hybrid functional
accuracy for geometries and harmonic frequencies in CCl$_3$F and other small
molecules    [PDF]

O. Anatole von Lilienfeld

Generalized gradient approximated (GGA) density functional theory (DFT) typically overestimates polarizability and bond-lengths, and underestimates force constants of covalent bonds. To overcome this problem we show that one can use empirical frequency correcting atom centered potentials (FCACPs), parameterized for every nuclear species. Parameters are obtained through minimization of a penalty functional that explicitly encodes hybrid DFT geometries and static polarizabilities of reference molecules. For hydrogen, fluorine, chlorine, and carbon the respective reference molecules consist of H$_2$, F$_2$, Cl$_2$, and CH$_4$. The transferability of this approach to other systems and properties is assessed for harmonic frequencies of a small set of molecules. Numerical evidence, gathered for CCl$_3$F, HF, HCl, CFH$_3$, and CHCl$_3$, indicates that the GGA+FCACP level of theory yields significantly improved harmonic frequencies at the desired hybrid DFT geometry minima, as well as systematically reduced molecular polarizability.

View original: http://arxiv.org/abs/1301.3225