Ab initio self-consistent total-energy calculations within the EXX/RPA formalism
Calculations of exact-exchange (EXX) and random phase approximation (RPA)-correlation energies within the formally exact adiabatic connection fluctuation-dissipation theorem formalism have recently been carried out for a number of isolated and condensed systems. Unfortunately, most of the applications have been done in a non-self-consistent procedure, and for several systems it has been found that RPA correlation energies may significantly depend on the choice of input single-particle wave functions. In this work, we develop an efficient approach to compute the EXX/RPA total energy self-consistently. We derive an expression for the RPA self-consistent potential based on the density functional perturbation theory and dielectric matrix approaches and implemented it within the plane-wave pseudopotential framework. The efficiency of this approach is greatly improved by exploiting an iterative procedure to compute the inverted Kohn-Sham density-density response function. We apply our implementation to study the binding energy curves and the structural properties of rare gasses such as Ar and Kr and alkaline-earth Be dimers. In addition, the EXX and RPA-correlation potentials of these systems at different dissociation distances are analyzed.