Center for Functional Nanomaterials Seminar

In recent years, there has been some revival of interest in the Random Phase Approximation (RPA) because the correlation energy calculated in RPA is an important ingredient of the so-called EXX/RPA+ scheme which provides a promising way to overcome the well-known drawback of LDA/GGA DFT in describing van der Waals systems. One of the main disadvantages of EXX/RPA+ scheme which limits its application to large systems is the computationally demanding calculations of RPA correlation energy. In this work, we will propose an efficient implementation for the calculation of RPA correction energy in the Adiabatic Connection Fluctuation-Dissipation (ACFD) formalism. We also explore an approach which allows further simplification, thus relevant for large systems, by using the Thomas - Fermi - von Weizsacker approximation of kinetic functional. The results of test applications to atomic and molecular systems show great promise, and thus opens the possibility to address large systems where correlations need to be treated beyond LDA and GGAs.