Testing several recent van der Waals density functionals for layered structures

摘要

Six recently developed exchanged functionals for pairing with different twoversions of van der Waals density functionals (vdW-DF) are tested for weaklybonded solids. The test, using 26 layered weakly bonded compounds, benchmarksthe lattice constants against experimental data and the interlayer bindingenergies against reference data from the random-phase approximation (RPA). Theinvestigated functionals tend to give interlayer binding energies higher thanthe RPA benchmark, and the overall performance for lattice constants is good.The exchange functionals optB86b and cx13 paired with the original vdW-DF andthe B86R functional paired with vdW-DF2 are found to give particularly goodresults for equilibrium geometries.