Non-covalent interactions between molecular dimers (S66) in electric fields

Abstract Fine tuning and microscopic control of van der Waals interactions through oriented external electric fields (OEEF) mandates an accurate systematic understanding intermolecular response properties. Having taken exploratory steps into this direction, we present a study interaction induced dipole properties all molecular dimers in the S66 set, relying on CCSD(T)-F12b/aug-cc-pVDZ-F12 as reference level theory. For field strengths up to $\approx$5 GV m$^{-1}$ beyond second order is found be insignificant. Large moments (i.e.~dipole moment changes due binding) are observed case hydrogen bonding along axis, mostly small bonded by $\pi$-stacking or London dispersion. The polarizabilities (i.e.~polarizability were generally but always with positive-valued principal component approximately aligned two other negative-valued components. Energy decompositions according symmetry adapted perturbation theory (SAPT0/jun-cc-pVDZ) suggest that electrostatics dominates moment, exchange induction contributing smaller scale, dispersion having smallest effect. First-order SAPT0 decomposition monomer-resolved contributions enables us establish quantitative link between monomers dimers, which qualitative agreement coupled cluster method. Using aug-cc-pVQZ basis non-empirical PBE semilocal exchange-correlation kernels, also assess how density functional approximations nonlocal correlation parts affect predictive accuracy: While dRPA@PBE0 based predictions excellent overall results, computationally more affordable LC-$\omega$PBE0-D3 yields reliable results relative errors below 5\%. alone, even when corrected, produces larger polarizabilities.