Explicitly correlated electronic structure theory from R12/F12 ansätze

Abstract Fundamental aspects of the explicitly correlated R12 and F12 theories are summarized in the perspective of recent advances related to our contribution in this field. Starting from the basics of pair functions and second quantized formulations, the R12/F12 ansätze have been applied to MP2, coupled‐cluster, and equation of motion coupled‐cluster theories. Emphasis is given to approaches that use the rational generator to create the exact cusp conditions (SP ansatz ). Computational aspects of the evaluation of many‐electron integrals are also discussed in conjunction with the use of the Slater‐type geminal, which is the predominant choice for the correlation factor in modern R12/F12 theories. © 2011 John Wiley & Sons, Ltd. This article is categorized under: Electronic Structure Theory > Ab Initio Electronic Structure Methods