Efficient Density-Fitted Explicitly Correlated Dispersion and Exchange Dispersion Energies

The leading-order dispersion and exchange-dispersion terms in symmetry-adapted perturbation theory (SAPT), Edisp(20) Eexch-disp(20), suffer from slow convergence to the complete basis set limit. To alleviate this problem, explicitly correlated variants of these corrections, Edisp(20)-F12 Eexch-disp(20)-F12, have been proposed recently. However, original formalism (M., Kodrycka , J. Chem. Theory Comput. 2019, 15, 5965-5986), while highly successful improving convergence, was not competitive conventional orbital-based SAPT computational efficiency due need manipulate several kinds two-electron integrals. In work, we eliminate by decomposing all types integrals using robust density fitting. We demonstrate that error fitting approximation is negligible when standard auxiliary bases such as aug-cc-pVXZ/MP2FIT are employed. new implementation allowed us study complexes A24 database sets up aug-cc-pV5Z, Eexch-disp(20)-F12 values exhibit vastly improved over their counterparts. well-converged numbers can be substituted for Eexch-disp(20) ones a calculation total interaction energy at any level (SAPT0, SAPT2+3, ...). show addition F12 does improve accuracy low-level treatments. errors minimized high-level approaches SAPT2+3(CCD)?MP2, reduction incompleteness thanks treatment substantially improves small-basis calculations.