  The lattice vibrations are determined in the quasi-harmonic approximation for
elemental Au and Cu to twice their normal density by first-principles
electronic band-structure calculations. It is found for these materials that
the important moments of the phonon density of states can be obtained to high
accuracy from short-ranged force constant models. We discuss the implications
for the Grueneisen parameters on the basis of calculated phonon moments and
their approximations by using bulk moduli and Debye-Waller factors.
