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DFT-D3 Study of Some Molecular Crystals
We investigate the performance of
the dispersion correction D3 with and without an explicit three-body
dispersion term for the energetic and structural properties of rare
gas and molecular crystals. Therefore, the two- and three-body gradient
of the dispersion energy is implemented in the periodic plane-wave
program VASP. It is combined with different density functionals at
the level of the general gradient approximation (GGA) and hybrid functionals.
Cohesive energies and lattice parameters for the rare gas crystals
Ar, Kr, and Xe and a set of 23 molecular crystals are calculated and
compared to experimental reference values. In general, all tested
methods yield very good results. For the molecular crystals the mean
absolute deviation of lattice energies from reference data (about
1–2 kcal/mol) is close to or below their uncertainties. The
influence of the three-body Axilrod–Teller–Muto dispersion
term on energy and structure is found to be rather small. While on
a GGA level cohesive energies become slightly worse, for hybrid functionals
the three-body term improves the results