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# Dispersion Energy of Symmetry-Adapted Perturbation Theory from the Explicitly Correlated F12 Approach

journal contribution

posted on 2018-09-06, 00:00 authored by Michał PrzybytekMethods
of the explicitly correlated F12 approach are applied to
the problem of calculating the uncoupled second-order dispersion energy
in symmetry-adapted perturbation theory. The accuracy of the new method
is tested for noncovalently bound complexes from the A24 data set
[J. Řezáč and P. Hobza,

*J. Chem. Theory Comput.***2013**,*9*, 2151] using standard orbital basis sets aug-cc-pV*X*Z supplemented with auxiliary aug-cc-pV*X*Z_OPTRI sets. For near equilibrium geometries, it is possible to recover the dispersion energy with average relative errors consistently smaller than 0.1% (with respect to the CBS extrapolated limit estimated from regular orbital calculations). This level of accuracy is achieved already in the basis set of a triple-ζ quality, when a Slater-type correlation factor exp(−0.9*r*_{12}) is combined with variant C of the F12 approach. The explicitly correlated approach clearly outperforms regular orbital calculations in the basis set of quintuple-ζ quality (average relative errors of 1%).