Weighted‐density‐functional theory calculation of elastic constants for face‐centered‐cubic and body‐centered‐cubic hard‐sphere crystals

Abstract

The isothermal elastic constants for the face‐centered‐cubic (fcc) and body‐centered‐cubic (bcc) hard‐sphere crystal are calculated for a range of densities using the modified weighted‐density functional of Denton and Ashcroft [Phys. Rev. A 3 9, 4701 (1989)]. The fcc elastic constants are shown to be in excellent agreement with the computer simulation data and to represent a significant improvement over the predictions of other density‐functional methods. The bcc crystal is predicted correctly to be unstable to shear, in agreement with simulation. This fact supports the conclusion that the bcc hard‐sphere solid, even though mechanically unstable, is well described by such methods.