Density-functional theory-symmetry-adapted intermolecular perturbation theory with density fitting: A new efficient method to study intermolecular interaction energies

Abstract

The previously developed DFT-SAPT approach, which combines symmetry-adapted intermolecular perturbation theory (SAPT) with a density-functional theory (DFT) representation of the monomers, has been implemented by using density fitting of two-electron objects. This approach, termed DF-DFT-SAPT, scales with the fifth power of the molecular size and with the third power upon increase of the basis set size for a given dimer, thus drastically reducing the cost of the conventional DFT-SAPT method. The accuracy of the density fitting approximation has been tested for the ethyne dimer. It has been found that the errors in the interaction energies due to density fitting are below 10(-3) kcal/mol with suitable auxiliary basis sets and thus one or two orders of magnitude smaller than the errors due to the use of a limited atomic orbital basis set. An investigation of three prominent structures of the benzene dimer, namely, the T shaped, parallel displaced, and sandwich geometries, employing basis sets of up to augmented quadruple-zeta quality shows that DF-DFT-SAPT outperforms second-order Moller-Plesset theory (MP2) and gives total interaction energies which are close to the best estimates inferred from combining the results of MP2 and coupled-cluster theory with single, double, and perturbative triple excitations.

Balance of Attraction and Repulsion in Nucleic-Acid Base Stacking: CCSD(T)/Complete-Basis-Set-Limit Calculations on Uracil Dimer and a Comparison with the Force-Field Description

“…DFT-SAPT interaction energies are usually underestimated when using this basis set, mainly because the dispersion component is underestimated by about 10-20%. 110 This underestimation does not change the conclusions regarding the relative importance of the individual contributions to the interaction energy given below. With a larger basis set DFT-SAPT was shown to provide very accurate total interaction energies in good agreement with the most accurate CCSD(T) calculations.…”

“…With a larger basis set DFT-SAPT was shown to provide very accurate total interaction energies in good agreement with the most accurate CCSD(T) calculations. 110 Using the aug-cc-pVDZ basis set for the IP calculations does not affect the shift values dramatically, and resulting errors should be smaller than the SAPT basis-setsize errors.…”

Vibration–rotation-tunneling states of the benzene dimer: an ab initio study

“…38 The ab initio method used was SAPT(DFT): symmetry-adapted perturbation theory (SAPT) based on monomer wave functions, orbital energies, and response properties obtained from (time-dependent) DFT calculations. This method, initially proposed by Williams and Chabalowski, 63 was later extended and implemented by Misquitta et al [64][65][66] and by Heßelmann et al 37,67,68 It is much more economical than the regular SAPT 69 or the coupledcluster method using single, double, and perturbative triple excitations, CCSD(T), the two approaches that have established themselves currently as the most accurate of practically applicable methods for obtaining intermolecular interaction potentials. Both groups have shown that SAPT(DFT) results for the benzene dimer are about as accurate as the results from CCSD(T).…”

Communication: Resolving the three-body contribution to the lattice energy of crystalline benzene: Benchmark results from coupled-cluster theory

“…4 Further estimates of three-body lattice energy contributions using symmetry-adapted perturbation theory based on densityfunctional descriptions of the monomers [SAPT(DFT)] [5][6][7][8][9][10][11][12] for crystalline benzene indicated that three-body effects contribute around 1.6 kcal mol −1 (or about 14% of the total lattice energy). 13 More recent studies 14,15 suggest that the majority of the three-body effects in crystalline benzene are due to three-body dispersion interactions, estimated to contribute 1.1 or 1.7 kcal mol −1 using the Axilrod-Teller-Muto expression (below).…”