ZMP-SAPT: DFT-SAPT using ab initio densities

Abstract

Symmetry Adapted Perturbation Theory (SAPT) has become an important tool when predicting and analyzing intermolecular interactions. Unfortunately, DFT-SAPT, which uses Density Functional Theory (DFT) for the underlying monomers, has some arbitrariness concerning the exchange-correlation potential and the exchange-correlation kernel involved. By using ab initio Brueckner Doubles densities and constructing Kohn-Sham orbitals via the Zhao-Morrison-Parr (ZMP) method, we are able to lift the dependence of DFT-SAPT on DFT exchange-correlation potential models in first order. This way, we can compute the monomers at the Coupled-Cluster level of theory and utilize SAPT for the intermolecular interaction energy. The resulting ZMP-SAPT approach is tested for small dimer systems involving rare gas atoms, cations, and anions and shown to compare well with the Tang-Toennies model and coupled cluster results.

Pinacolone-Alcohol Gas-Phase Solvation Balances as Experimental Dispersion Benchmarks

“…This is a refined way of obtaining such (strictly speaking non-observable) dispersion energies, which is conceptually better than simply evaluating the size of the D3 correction in the complex (Table S13). In the present case, the numbers obtained for both methods are quite similar, but this cannot be generalized except perhaps for large distances, where London dispersion is best defined and LED [16], SAPT [18] or empirical dispersion correction [26] should become comparable as leading corrections to long range electrostatic and inductive interactions. Dispersion always favors tBu docking, by 1.5 to 3.1 kJ mol −1 in the LED scheme (1.6 to 2.8 kJ mol −1 for D3 corrections).…”

“…The results of such studies can be used to benchmark the ability of different density functionals to predict the interplay of hydrogen bonding with distant London dispersion and Pauli repulsion, by simply comparing the predictions to experiment. This can be done strictly at the level of observables, without consulting any energy decomposition models [16][17][18], although the latter are helpful in the interpretation of the findings. A functional which gives the right answer for the right reason in the popular harmonic approximation for vibrations must be able to predict the splitting of the OH stretching vibrations between the docking isomers (because anharmonic effects by construction largely cancel when comparing the isomers) and the relative abundance of the isomers with a reasonable conformational temperature.…”

Recent developments in symmetry‐adapted perturbation theory

“…In the more general case, SAPT(DFT) calculations employing an ab initio derived potential, computed from Brueckner doubles densities using the Zhao-Morrison-Parr (ZMP) 358 method, and the ALDA exchange correlation kernel have been investigated by Boese and Jansen. 359 The resulting SAPT(ZMP) approach showed an overall improved performance over SAPT(DFT), in particular, essentially removing the overbinding of the latter in the case of rare gas dimers. 360…”

“…Such a procedure was used in the early SAPT(DFT) work of Hesselmann and Jansen to derive an essentially exact exchange‐correlation potential for use in SAPT(DFT) calculations for the helium dimer. In the more general case, SAPT(DFT) calculations employing an ab initio derived potential, computed from Brueckner doubles densities using the Zhao‐Morrison‐Parr (ZMP) method, and the ALDA exchange correlation kernel have been investigated by Boese and Jansen . The resulting SAPT(ZMP) approach showed an overall improved performance over SAPT(DFT), in particular, essentially removing the overbinding of the latter in the case of rare gas dimers …”

Assessment of SAPT(DFT) with meta-GGA functionals

“…Holzer and Klopper developed SAPT based on quasiparticle energies and response functions from the GW method [7]. Boese and Jansen used accurate densities to construct Kohn-Sham (KS) exchange-correlation potentials for use in SAPT [8]. Korona employed CCSD density matrices and response functions in the formulation of SAPT(CCSD) which also bypasses double-perturbation theory [9].…”