Exact exchange for correlated electrons

A density functional based exact exchange for correlated electrons (EECE) method of electronic structure determination, intended as an improved initial point for the description of systems containing correlated electrons, is proposed and its implementation is described. This approach bears strong resemblance to certain methods already in use: in implementation it is much like the LDA+U method with the important distinction that it is parameter-free; in concept has much in common with previous `exact exchange' and self-interaction corrected approaches. The EECE method is applied to several systems with varying correlation strengths and characters (FeF2, NiO, hcp Gd, FeAl) and the results are compared with those obtained by LDA +U and Hartree-Fock methods as well as results within the local spin density and generalized gradient approximations to density functional theory. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.