Fast and Reliable Evaluation of Intermolecular Interactions with Second-Order Møller-Plesset Perturbation Theory and Small Basis Set

Following a procedure already applied to double-hybrid functionals within the density functional theory framework, a new basis set is developed to improve the performances of the second-order Møller−Plesset (MP2) approach in evaluating noncovalent interactions. This procedure does not require any specific parametrization of the underlining MP2 approach so that its ab initio nature is not affected. The new basis set is derived using a self-consistent formula, containing only energy terms all computed at the same level of theory, for optimizing a few exponents of the small def2-SVP basis. The transferability and robustness of the obtained basis set, named MP-SVP, have been then verified on 5 benchmark sets, including also halogenated molecules and energy dissociation profiles. The obtained results show that the MP-SVP basis set is more accurate than the CBS extrapolation on the considered tests and can be successfully used in simple composite approaches, such as MP2.5