Van der Waals Interaction between P-4 Molecules: Density Functional Theory Calculations with Dispersion Correction

Abstract

We investigated the structural and the binding properties of tetrahedral P-4 molecular pairs by employing density functional theory (DFT) calculations using both the local density approximation (LDA) and the generalized gradient approximation (GGA). To consider the van der Waals interaction, we employed the GGA with dispersion correction, specifically Grimme's approach (DFT-D2). This DFT-D2 in conjunction with the GGA (GGA-D2) well fixes the failure of the GGA in reproducing a reasonable binding energy curve. The binding energy and the equilibrium intermolecular distance are found to be in close correlation with the number of adjacent atomic pairs between two molecules. Application of the LDA and the GGA-D2 to a molecular crystal beta-P-4 and comparison with experiments confirms that the GGA-D2 should be used for a reliable description of P-4-based molecular systems.