Effect of dispersion corrections on covalent and non-covalent interactions in DFTB calculations

Dispersion corrections in quantum mechanical methods with the focus on non-covalent interactions have been extensively investigated in the past decade. In this paper, we elucidate the role of dispersion corrections in both non-covalent and covalent interactions within the density functional tight binding (DFTB) method. Our results suggest that two dispersion correction models, D3(BJ) and D3(CSO), generally improve different properties including barrier heights, isomerization energies, bond dissociation energies, and non-covalent binding energies. The D3(CSO) model, with fewer dispersion coefficients and DFTB-dependent parameters, was shown to perform as well as the D3(BJ) model.