DIELECTRIC FUNCTION AND PLASMON EXCITATIONS IN SILVER

The microscopic dielectric function of silver is investigated in the f ramework of the time-dependent density-functional theory underlying a spline augmented plane-wave band calculation. A reasonable overall agr eement is found when comparing our results with experimental data. Sma ll systematic errors in the position of the peaks can be ascribed to t he local density approximation. It is shown that in the long-wave limi t a zero of the diagonal element corresponds to a plasmon excitation. The frequency of the q = 0 plasmon excitation agrees quite well with i ts experimental value. No plasmon excitation can be found even for sme ll values of the propagation vector.