New Approach for Correcting Noncovalent Interactions in Semiempirical Quantum Mechanical Methods: The Importance of Multiple-Orientation Sampling

A new approach is presented to improve the performance of semiempirical quantum mechanical (SQM) methods in description noncovalent interactions. To show strategy, PM6 Hamiltonian was selected, although, general, procedure can be applied other Hamiltonians and different methodologies. set small molecules were selected as representative various functional groups, intermolecular potential energy curves (IPECs) evaluated for most relevant orientations interacting molecular pairs. Then, analytical corrections derived from fits B3LYP-D3/def2-TZVP reference–PM6 interaction differences. IPECs provided by combination electronic structure method basis chosen reference because they are excellent agreement with CCSD(T)/aug-cc-pVTZ studied systems. The resulting method, called PM6-FGC (from group corrections), significantly improves shows importance including a sufficient number data order obtain well-balanced descriptions.