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 results obtained document that this EECE method gives results closely related to those obtained with the Hartree–Fock method. EECE is implemented in the WIEN2k code, based on the FLAPW approach to the density functional theory. EECE is relatively transparent and it has very little additional requirements on computer time and memory. It is promising starting point for the further improvement of orbital-dependent density functionals.