Nonlocal pseudopotential formulation for lattice dynamics. II : application to sodium

The formulation proposed earlier for the lattice dynamics of simple metals using the pseudopotential method with a non-local pseudopotential has been applied to calculate the phonon frequencies of sodium along the symmetry directions. The bound wave functions are evaluated numerically and their Fourier transforms are obtained by approximating the numerical functions by suitable analytic functions. The agreement of the calculated phonon frequencies with the experimental data is fairly satisfactory