Accurate description of van der Waals complexes by density functional theory including empirical corrections

Abstract

An empirical method to account for van der Waals interactions in practical calculations with the density functional theory (termed DFT-D) is tested for a wide variety of molecular complexes. As in previous schemes, the dispersive energy is described by damped interatomic potentials of the form C6R(-6). The use of pure, gradient-corrected density functionals (BLYP and PBE), together with the resolution-of-the-identity (RI) approximation for the Coulomb operator, allows very efficient computations for large systems. Opposed to previous work, extended AO basis sets of polarized TZV or QZV quality are employed, which reduces the basis set superposition error to a negligible extend. By using a global scaling factor for the atomic C6 coefficients, the functional dependence of the results could be strongly reduced. The "double counting" of correlation effects for strongly bound complexes is found to be insignificant if steep damping functions are employed. The method is applied to a total of 29 complexes of atoms and small molecules (Ne, CH4, NH3, H2O, CH3F, N2, F2, formic acid, ethene, and ethine) with each other and with benzene, to benzene, naphthalene, pyrene, and coronene dimers, the naphthalene trimer, coronene. H2O and four H-bonded and stacked DNA base pairs (AT and GC). In almost all cases, very good agreement with reliable theoretical or experimental results for binding energies and intermolecular distances is obtained. For stacked aromatic systems and the important base pairs, the DFT-D-BLYP model seems to be even superior to standard MP2 treatments that systematically overbind. The good results obtained suggest the approach as a practical tool to describe the properties of many important van der Waals systems in chemistry. Furthermore, the DFT-D data may either be used to calibrate much simpler (e.g., force-field) potentials or the optimized structures can be used as input for more accurate ab initio calculations of the interaction energies.

Computational design of faster rotating second-generation light-driven molecular motors by control of steric effects

“…In our previous study, 57 the range-separated and dispersion-corrected 58,59 ωB97X-D 60 hybrid density functional showed good overall performance for the full rotary cycle of the original type Ia Feringa motor. Therefore, it was decided to use this method also in the present work.…”

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

“…In this equation d is a parameter determining the steepness of the damping function, and s R is a scaling coefficient that adjusts the magnitude of the vdW radius and that has been determined for several density-functional/basis-set combinations. The values of the C 6 atomic coefficients have been taken from the work of Grimme, 101 whereas the d and s R parameters as well as the combination rules for the vdW radii and the composite dispersion coefficients are the same as those in the work of Jurečka et al 53 Here we use the TPSS 102 functional along with the 6-311++G(3df,3pd) 36 basis set. This level of theory complemented with the dispersion correction will hereafter be referred to as DFT-D. 104,105 approximations.…”

Dispersion corrected DFT approaches for anharmonic vibrational frequency calculations: nucleobases and their dimers

“…Unfortunately, standard functionals fail in describing such non-local and non-classical electronic interactions 108 . Instead, this type of interactions can be modelled at a relatively low computational cost by using dispersion-corrected DFT methods [109][110][111] and new functionals [112][113][114][115] . However, some of the most successful lastgeneration functionals (M06-2X 113 and ωB97X 114,116 ) do not predict vibrational wavenumbers with an accuracy sufficient for spectroscopic studies 31,89,90,117 .…”