An Efficient a Posteriori Treatment for Dispersion Interaction in Density-Functional-Based Tight Binding

Abstract

The performance of density functional theory (DFT) (VWN-LDA, PBE-GGA, and B3LYP hybrid functionals), density-functional-based tight binding (DFTB), and ab initio methods [HF, MP2, CCSD, and CCSD(T)] for the treatment of London dispersion is investigated. Although highly correlated ab initio methods are capable of describing this phenomenon, if they are used with rather large basis sets, DFT methods are found to be inadequate for the description of H2/PAH (polycyclic aromatic hydrocarbon) interactions. As an alternative approach, an a posteriori addition of a van der Waals term to DFTB is proposed. This method provides results for H2/PAH interactions in close agreement with MP2 and higher-level ab initio methods. Bulk properties of graphite also compare well with the experimental data.

A Comparative Density Functional Theory and Density Functional Tight Binding Study of Phases of Nitrogen Including a High Energy Density Material N8

“…Atomic positions and lattice vectors were optimized until atomic forces are below 0.01 eV/Å. Dispersion interactions were modeled with the UFF (Universal Force Field) scheme [41,42]. Note that different types of dispersion correction are available in SIESTA and DFTB+, but this is not critical as long as we achieve our purpose of reproducing structures and relative energies of different phases with both methods.…”

Implementation of the SCC-DFTB Method for Hybrid QM/MM Simulations within the Amber Molecular Dynamics Package

“…41,42 Efforts have been made to correct for this behavior as an a posteriori addition to DFTB. 43,44 The method used in the AMBER implementation follows Elstner et al, 43 where an empirical correction is applied to the DFTB energy expression to yield: (13) The parameters are derived from experimental atomic polarizabilities and the damping function f(R αβ ) adjusted in order to reproduce a large set of reference data. 43 The damping function used in the AMBER implementation is the same as in Elstner's work: 43 (14) with the same values of d=3.0, N=7 and M=4 for all atoms, and calculated by a combination rule: (15) using for H, 3.8Å for C, N and O, and 4.8Å for P and S atoms.…”

Defects in alpha and gamma crystalline nylon6: A computational study

“…The parameter set (Slater-Koster files) 3ob-2-1 which has been benchmarked for organic systems including non-covalent bonds is used in this study. 16,17 Dispersion corrections based on the UFF force field were used 18,19 with the parameters taken from the study of Zhechkov et al 20 Large periodic simulation cells were used with 1368 atoms for both α and γ phases. The large cells are required to model defected systems and justify the use of the tight-binding approach.…”