Abstract:
van der Waals (vdW) energy corrected density-functional theoryis applied to study the cohesive properties of ionic and semiconductor solids (C, Si, Ge, GaAs, NaCl, andMgO). The required polarizability and dispersion coefficients are calculated using the dielectric functionobtained from time-dependent density-functional theory. Coefficients for ‘‘atoms in the solid’’ are thencalculated from the Hirshfeld partitioning of the electron density. It is shown that the Clausius-Mossottiequation that relates the polarizability and the dielectric function is accurate even for covalently-bonded semiconductors. We find an overall improvement in the cohesive properties of Si, Ge, GaAs, NaCl, andMgO, when vdW interactions are included on top of the Perdew-Burke-Ernzerhof or Heyd-Scuseria-Ernzerhof functionals. The relevance of our findings for other solids is discussed.
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