Functional group corrections to the GFN2-xTB and PM6 semiempirical methods for noncovalent interactions in alkanes and alkenes

Abstract

Analytical corrections were developed to improve the accuracy of the PM6 and GFN2-xTB semiempirical quantum mechanical (SQM) methods for the evaluation of noncovalent interaction energies in alkanes and alkenes. We followed the approach of functional group corrections (FGC), wherein the atom-atom pair corrections depend on the nature of the interacting functional groups. The training set includes 21 alkane and 13 alkene complexes taken from the Donchev’s database [Scientific Data 8 (2021) 55], with interaction energies calculated at the CCSD(T)/CBS level, as well as our own data obtained for medium-size complexes (of 100 and 112 atoms). In general, for the systems included in the training and validation sets, the errors obtained with the PM6-FGC and xTB-FGC methods are within chemical accuracy.