AllhaxxxxOII1C PhOIIOIIS 111 C8

The dynamic form factor S'(Q, xo) and, the phonon frequencies and hfetlmes in Cs at T=5, 90, and 290 K are calculated. The anharmonic properties of Cs are apparently dominated by the cubic anharmonic term. Properties such as anharmonic interference in S(Q,to) which is proportional to the cubic term are found to be relatively large and should be readily observable at high temperature. The most interesting phonons are the longx'tudinal phonons along the [100] direction at high Q, which have the shortest Hfetimes, and the T~ phonons along [110) which are very sensitive to anharmonic contributions.