Intermolecular potentials based on symmetry-adapted perturbation theory with dispersion energies from time-dependent density-functional calculations

Abstract

Recently, three of us have proposed a method [Phys. Rev. Lett. 91, 33201 (2003)] for an accurate calculation of the dispersion energy utilizing frequency-dependent density susceptibilities of monomers obtained from time-dependent density-functional theory (DFT). In the present paper, we report numerical calculations for the helium, neon, water, and carbon dioxide dimers and show that for a wide range of intermonomer separations, including the van der Waals and short-range repulsion regions, the method provides dispersion energies with accuracies comparable to those that can be achieved using the current most sophisticated wave-function methods. If the dispersion energy is combined with (i) the electrostatic and first-order exchange interaction energies as defined in symmetry-adapted perturbation theory (SAPT) but computed using monomer Kohn-Sham (KS) determinants, and (ii) the induction energy computed using the coupled KS static response theory, (iii) the exchange-induction and exchange-dispersion energies computed using KS orbitals and orbital energies, the resulting method, denoted by SAPT(DFT), produces very accurate total interaction potentials. For the helium dimer, the only system with nearly exact benchmark values, SAPT(DFT) reproduces the interaction energy to within about 2% at the minimum and to a similar accuracy for all other distances ranging from the strongly repulsive to the asymptotic region. For the remaining systems investigated by us, the quality of the SAPT(DFT) interaction energies is so high that these energies may actually be more accurate than the best available results obtained with wave-function techniques. At the same time, SAPT(DFT) is much more computationally efficient than any method previously used for calculating the dispersion and other interaction energy components at this level of accuracy.

Linewidths of C2H2 perturbed by H2: experiments and calculations from an ab initio potential

“…To perform the calculations, we have used the Molpro package [45] which permits the use of ab initio methods such as: the Hartree-Fock (HF) method, the second order Møller-Plesset perturbation theory (MP2), the coupled cluster method at a level of single and double excitations with the triple excitations included perturbatively, i.e. CCSD(T), and the symmetry adapted perturbation method based on monomer orbitals built up with the density functional theory (SAPT(DFT)) [42]. Several atomic basis sets have been tested: the augmented -correlation consistent -polarized triple and quadruple zeta basis sets (augcc-pVXZ with X=T and Q) and the polarization optimized Sadlej basis set [46].…”

“…Significant progress has been made in the ab initio computation of intermolecular interactions. Methods like coupled cluster or symmetry adapted perturbation theory (SAPT) [39][40][41] together with its more recent extension SAPT(DFT) based on the density functional theory [42] enable the determination of van der Waals intermolecular potentials between closed-shell systems with spectroscopic accuracy. After comparative tests between the available ab initio methods, we retain the CCSD(T) method for the determination of the C 2 H 2 -H 2 PES.…”

Charge Transfer from Regularized Symmetry-Adapted Perturbation Theory

“…For details see Ref. 22. The second-order induction energies were evaluated using the hybrid form of the linear-response kernel [5,22].…”

“…22. The second-order induction energies were evaluated using the hybrid form of the linear-response kernel [5,22]. E (2) ind,exch was evaluated without scaling [5] using the expressions in Refs.…”

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).…”