Benchmark data base for accurate van der Waals interaction in inorganic fragments

A range of inorganic materials, such as Sb, As, P, S, Se are built from van der Waals (vdW) interacting units forming the crystals, which neither the standard DFT GGA description as well as cheap quantum chemistry methods, such as MP2, do not describe correctly. We use this data base, for which have performed ultra accurate CCSD(T) calculations in complete basis set limit, to test the alternative approximate theories, such as Grimme [1], Langreth-Lundqvist [2], and Tkachenko-Scheffler [3]. While none of these theories gives entirely correct description, Grimme consistently provides more accurate results than Langreth-Lundqvist, which tend to overestimate the distances and underestimate the interaction energies for this set of systems. Contrary Tkachenko-Scheffler appear to yield surprisingly accurate and computationally cheap and convenient description applicable also for systems with appreciable charge transfer. \\[4pt] [1] S. Grimme, J. Comp. Chem. \textbf{27}, 1787 (2006) \\[0pt] [2] K. Lee, \textit{et al.}, Phys. Rev. B 82 081101 (R) (2010) \\[0pt] [3] Tkachenko and M. Scheffler Phys. Rev. Lett. \textbf{102} 073005 (2009).