Keywords :
Atoms; Carrier concentration; Electron density measurement; Electronic structure; Electrons; Van der Waals forces; Atom in a molecules; Bonding environments; Correction methods; Damping functions; Density-functional theory calculations; Electron densities; Electronic structure calculations; Exchange-correlation functional; Experimental values; Free atoms; Ground-state electrons; Mean absolute errors; Mean fields; Parameter-free methods; Reference datum; Van der waals interactions; Van der Waals radius; Density functional theory
Abstract :
[en] We present a parameter-free method for an accurate determination of long-range van der Waals interactions from mean-field electronic structure calculations. Our method relies on the summation of interatomic C6 coefficients, derived from the electron density of a molecule or solid and accurate reference data for the free atoms. The mean absolute error in the C6 coefficients is 5.5% when compared to accurate experimental values for 1225 intermolecular pairs, irrespective of the employed exchange-correlation functional. We show that the effective atomic C6 coefficients depend strongly on the bonding environment of an atom in a molecule. Finally, we analyze the van der Waals radii and the damping function in the C6R-6 correction method for density-functional theory calculations. © 2009 The American Physical Society.
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