Density fluctuation in a ‘‘Theorist’s ideal glass’’

Abstract

The density fluctuation in glassy materials can be considered to consist of dynamic and quasistatic contributions, the dynamic part being related to the compressibility of the glass determined on the same experimental time scale as the measurement of the density fluctuation. A justification for such an assumption, and a clarification of the meanings of the terms dynamic and quasistatic density fluctuation are obtained through the concept of ‘‘theorist’s ideal glass’’ which was originally described by Edwards for a canonical ensemble but now extended for a grand canonical ensemble.