Single-particle properties of systems undergoing structural phase transitions

We study the properties of the single-particle probability density function for a d-dimensional model system exhibiting a structural phase transition. Using renormalization-group methods (in d=1) and exact inequalities (in d=3), we examine, in particular, the extent to which the behavior of this function can reveal the distinctive changeover in dynamical behavior expected for a system exhibiting a displacive phase transition. © 1977 The American Physical Society.