Correlation energy expressions from the adiabatic-connection   fluctuation-dissipation theorem approach
  We explore several random phase approximation (RPA) correlation energy variants within the adiabatic-connection fluctuation-dissipation theorem approach. These variants differ in the way the exchange interactions are treated. One of these variants, named dRPA-II, is original to this work and closely resembles the second-order screened exchange (SOSEX) method. We discuss and clarify the connections among different RPA formulations. We derive the spin-adapted forms of all the variants for closed-shell systems, and test them on a few atomic and molecular systems with and without range separation of the electron-electron interaction. 
J\'anos G. Angy\'an (CRM2), Ru-Fen Liu (CRM2), Julien Toulouse (LCT),   Georg Jansen
physics.chem-ph physics.comp-ph