• Home
  • Search Results
  • Comparison of some dispersion-corrected and traditional functionals with CCSD(T) and MP2 ab initio methods: dispersion, induction, and basis set superposition error.

Comparison of some dispersion-corrected and traditional functionals with CCSD(T) and MP2 ab initio methods: dispersion, induction, and basis set superposition error.

The Journal of chemical physics (2012-10-09)
Dipankar Roy, Mateusz Marianski, Neepa T Maitra, J J Dannenberg
ABSTRACT

We compare dispersion and induction interactions for noble gas dimers and for Ne, methane, and 2-butyne with HF and LiF using a variety of functionals (including some specifically parameterized to evaluate dispersion interactions) with ab initio methods including CCSD(T) and MP2. We see that inductive interactions tend to enhance dispersion and may be accompanied by charge-transfer. We show that the functionals do not generally follow the expected trends in interaction energies, basis set superposition errors (BSSE), and interaction distances as a function of basis set size. The functionals parameterized to treat dispersion interactions often overestimate these interactions, sometimes by quite a lot, when compared to higher level calculations. Which functionals work best depends upon the examples chosen. The B3LYP and X3LYP functionals, which do not describe pure dispersion interactions, appear to describe dispersion mixed with induction about as accurately as those parametrized to treat dispersion. We observed significant differences in high-level wavefunction calculations in a basis set larger than those used to generate the structures in many of the databases. We discuss the implications for highly parameterized functionals based on these databases, as well as the use of simple potential energy for fitting the parameters rather than experimentally determinable thermodynamic state functions that involve consideration of vibrational states.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Hydrofluoric acid, ACS reagent, 48%
Sigma-Aldrich
Hydrofluoric acid, 48 wt. % in H2O, ≥99.99% trace metals basis
Sigma-Aldrich
Hydrofluoric acid, puriss. p.a., ACS reagent, reag. ISO, reag. Ph. Eur., ≥48%
Sigma-Aldrich
Lithium fluoride, ≥99.99% trace metals basis
Sigma-Aldrich
Lithium fluoride, powder, -300 mesh
Sigma-Aldrich
Lithium fluoride, powder, <100 μm, ≥99.98% trace metals basis
Sigma-Aldrich
Hydrofluoric acid, puriss. p.a., reag. ISO, reag. Ph. Eur., ≥40%
Sigma-Aldrich
Lithium fluoride, Precipitated, 99.995%
Sigma-Aldrich
Lithium fluoride, BioUltra, ≥99.0% (F)
Sigma-Aldrich
Lithium-6Li fluoride, 95 atom % 6Li, 99% (CP)