Interaction between n-Alkane Chains:  Applicability of the Empirically Corrected Density Functional Theory for Van der Waals Complexes

Abstract

The geometries, interaction energies, and vibrational frequencies of a series of n-alkane dimers up to dodecane have been calculated using density functional theory (DFT) augmented with an empirical dispersion energy term (DFT-D). The results obtained from this method for ethane to hexane dimers are compared with those provided by the MP2 level of theory and the combined Gaussian-3 approach with CCSD(T) being the highest correlation method [G3(CCSD(T))]. Two types of dimer isomers have been studied. The most stable isomers have the two carbon chains in parallel planes, whereas the second ones have the two carbon chains in the same plane. Butane is found to be the shortest carbon chain to form dimers with similar properties, that is, a constant average distance between the monomer carbon skeletons, a similar increment per CH2 unit for the dimer interaction energy, and comparable dimer symmetric stretching frequencies. The values and trends obtained from the DFT-D approach agree very well with those obtained from MP2 for the geometries and vibrational frequencies and from the G3(CCSD(T)) method for the energies, validating the use of DFT-D for the study of large hydrocarbon complexes.

Long-range corrected hybrid density functionals with damped atom–atom dispersion corrections

“…Following the general form of the DFT-D scheme [30][31][32][33][34][35][36][37][38][39][40][41][42][43], our total energy…”

“…Such an approach was used long ago to correct HF calculations [29], and over the past 8 years has been incorporated into density functional theory [30][31][32][33][34][35][36][37][38][39][40][41][42][43]. These DFT-D (density functional theory with empirical dispersion corrections) schemes have shown generally satisfactory performance on a large set of non-covalent systems [35,40].…”

Study of template interactions in MFI and MEL zeolites using quantum methods

“…Dispersion interactions with empirical corrections to the energy, (DFT-D) [24] were employed in order to include some electron correlation effects at larger distances that provide relatively good descriptions of the van der Waals forces and hydrogen bonds. A DZVP basis set was employed.…”

Density-functional-based tight-binding parameterization of Mo, C, H, O and Si for studying hydrogenation reactions on molybdenum carbide

“…However, the PBE functional form in DFT contains a significant amount of correlation effect [38] in this range to be sensitive enough to the electron density difference in the second layer. Also, the correction of PBE by the damped dispersion term [39] may also contribute to the difference between DFT and DFTB. As such, the accuracy of the adsorption energies may be affected if dispersion corrections are accounted for in a different way.…”