Aksu, Huseyin2025-01-272025-01-2720121432-881X1432-2234https://doi.org/10.1007/s00214-012-1285-9https://hdl.handle.net/20.500.12428/22124Size-extensivity correction to second-order Brillouin-Wigner perturbation theory is derived and implemented. For the size-extensivity correction, renormalization term is obtained by modifying the non-physical term in the denominator of the second-order Brillouin-Wigner formulae. We have achieved improved results. The method is illustrated in a series calculations on H2O, BH, HOF, Be and Ne using three different basis sets, and the results are then compared with corresponding coupled cluster double and second-order MOller-Plesset perturbation theory.eninfo:eu-repo/semantics/closedAccessMany electron theorySize-extensivity correctionMOller-Plesset perturbation theoryBrillouin-Wigner perturbation theoryRenormalization termArticle1311110.1007/s00214-012-1285-9Q2WOS:0003120762000032-s2.0-84867589618Q3