Quantum effects in an n-component vector model for structural phase transitions

The influence of quantum effects on the critical properties of an n-component vector model for structural phase transitions is explored. It is shown for n = 1, 2, and that these effects can suppress the occurrence of a phase transition for all dimensions d. This turns out to be of particular relevance for systems where the classical transition temperature almost vanishes (Tc=0 represents the displacive limit). We also discuss the critical properties at this limit for n = and show that the critical exponents change discontinously. © 1976 The American Physical Society.