Force correcting atom centered potentials for generalized gradient approximated density functional theory: Approaching hybrid functional accuracy for geometries and harmonic frequencies in small chlorofluorocarbons

摘要

Generalized gradient approximated (GGA) density functional theory (DFT)typically overestimates polarizability and bond-lengths, and underestimatesforce constants of covalent bonds. To overcome this problem we show that onecan use empirical force correcting atom centered potentials (FCACPs),parameterized for every nuclear species. Parameters are obtained throughminimization of a penalty functional that explicitly encodes hybrid DFT forcesand 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 is assessed forharmonic frequencies in a small set of chlorofluorocarbon molecules. Numericalevidence, gathered for CF$_4$, CCl$_4$, CCl$_3$F, CCl$_2$F$_2$, CClF$_3$, ClF,HF, HCl, CFH$_3$, CF$_2$H$_2$, CF$_3$H, CHCl$_3$, CH$_2$Cl$_2$, CH$_3$Clindicates that the GGA+FCACP level of theory yields harmonic frequencies thatare significantly more consistent with hybrid DFT values, as well as slightlyreduced molecular polarizability.