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Functional group corrections to the GFN2-xTB and PM6 semiempirical methods for noncovalent interactions in alkanes
Enrique M Cabaleiro-Lago1, Berta Fernández1, Roberto Rodríguez-Fernández1
1Departamento de Química Física, Facultade de Química, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Abstract:
Analytical corrections were developed to improve the accuracy of the PM6 and GFN2-xTB semiempirical quantum mechanical methods for the evaluation of noncovalent interaction energies in alkanes and alkenes. We followed the approach of functional group corrections, 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 et al.'s database [Sci. Data 8, 55 (2021)], with interaction energies calculated at the CCSD(T)/CBS level, and 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 the chemical accuracy.
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