The moment-expansion technique for the calculation of spectral functions is applied to a realistic model of argon for which molecular-dynamics results have previously been obtained. The first five even moments, ${\mathrm{\mu }}_0$ to ${\mathrm{\mu }}_8$, are calculated in a classical Monte Carlo simulation. Various methods of terminating the continued fraction expansion for the spectral function are tested. When a Gaussian model spectrum is used to supplement the calculated moments, the peak center is accurately located and the height and width of the peak are given to about 20% accuracy.

• Received 11 July 1994

DOI:https://doi.org/10.1103/PhysRevB.50.16380