Lattice Energies and Elastic Properties of Solid Methane: Assessment of Different Density Functionals

The performance of density functional theory (DFT) with and without dispersion energy correction for describing van der Waals (vdW) systems is evaluated by calculating the crystal structure, lattice energy, and elastic properties of solid methane. The results obtained from DFT with different exchange-correlation functionals (including some hybrid functionals) and from DFT with dispersion energy correction (DFT-D) methods are compared with experimental values. Although the DFT-D methods typically perform better than the standard and hybrid DFT functionals, some of them overcorrect the vdW interaction in solid methane. Thus, one must be cautious when using DFT-D methods.