A scaled explicitly correlated F12 correction to second-order Møller–Plesset perturbation theory

An empirically scaled version of the explicitly correlated F12 correction to second-order Møller–Plesset perturbation theory (MP2-F12) is introduced. The scaling eliminates need for many most costly terms while reproducing unscaled interaction energy a high degree accuracy. method requires single, basis set dependent factor that determined by fitting test molecules. We present factors cc-pVXZ-F12 (X = D, T, Q) family obtained minimizing energies S66 small- medium-sized molecular complexes and show our new can be applied accurately describe wide range systems. Remarkably good corrections are S22 L7 sets, with mean percentage errors double-zeta 0.60% energy, 0.05% total electron correlation 0.03% respectively. Additionally, introduced approach below 0.01 kcal mol−1 each thus negligible based methods. efficiency compared shown all considered systems, distinct speedups medium- large-sized structures.