Structural and vibrational properties of $\alpha$-MoO${}_3$ are studied employing two recently proposed methodologies for incorporating van der Waals (vdW) contributions in density functional theory (DFT) based calculations. The DFT-D2 [S. Grimme, J. Comput. Chem. 27, 1787 (2006)] and optB88 vdW-DFT [J. Klimeš et al., J. Phys.: Condens. Matter 22, 022201 (2010)] methods are shown to give rise to increased accuracy in predicted lattice parameters, relative to conventional DFT methods. Calculated vibrational frequencies agree with measurements to within 5$\%$ and 10$\%$ for modes involving bonded and nonbonded interactions in this compound, respectively.

• Received 4 October 2011

DOI:https://doi.org/10.1103/PhysRevB.85.012104