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three (in the unbiased case these would all be 25%).Since the relative maximum in density at (0.4 0 0.4) in Fig. 2 is situated essentially along the line joining ''f sites, it is relevant to ask whether this site plays a role as a residence site. When the density is plotted from one "f site to another, the location (0.4 0 0.4) is a local mini-' mum and not a maximum; along this line the values of the density decrease from unity at (iO i) to 0.63 at (0.31 00.44) and then to 0.37 at (0.375 0 0.375), point S. A concise manner of describing the situation is that the Ag ions reside at the *'t'* sites for about 3 psec, developing a thermal cloud of half-width 0.6 A in the (100) plane and move between the **f' sites along rather narrow channels.The work reported here makes it quite clear that using classic notions regarding the interparticle potentials in ionic materials it is possible to construct model systems which reproduce with fair precision the observed structural and dynamical behavior of a-Agl. We are therefore proceeding further on an analysis of the structure and properties of other forms of Agl as well as other materials like Cul. The analysis of density fluctuations in Q?-Agl is now in progress.We evaluate the lifetime of quaslpartlcles in the Fermi glass. An anomalous contribution to the lifetime is found. It is shown that this effect leads to a T^^^ law for the dc conductivity of a disordered system.

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