Local Hybrid Functionals with an Explicit Dependence on Spin Polarization

摘要

A new family of local hybrid functionals with a position-dependent mixture of local and exact exchange hasbeen constructed. On the basis of conceptual similarities between local hybrids and explicit nondynamicalcorrelation functionals, the relative spin polarization has been introduced as an additional variable into thelocal mixing function (LMF) that determines the position dependence of the exact exchange admixture. Thisleads to two new two-parameter LMFs, one based on the ratio of the local kinetic energy density to the vonWeizsacker kinetic energy density and the other on the dimensionless density gradient. After optimization ofthe two free parameters for small test sets, significant improvements of atomization energies of the full G3set are obtained (mean absolute errors of 2.96 and 3.18 kcal respectively), with minor deteriorationfor classical reaction barriers (HTBH38 and NHTBH38 test sets). The simultaneous description of two-center three-electron dimer cations remains a challenge. It is shown that the exact and local spin densityexchange energy densities have closely related gauge definitions, so that gauge mismatch is only a minorproblem for local hybrids based on local exchange.