FLUCTUATIONS IN AN ASYMMETRIC ANHARMONIC CRYSTAL

In this paper we continue the investigation of the structural phase tr ansition in a quantum anharmonic crystal. We calculate the influence o f breaking the symmetry of the interaction potential on the behaviour of fluctuations and their critical exponents. More precisely, it is sh own that when the low-momentum asymptotics of the phonon spectrum (i.e . the Fourier transform of the interaction matrix) have a quartic asym ptotic in one direction, the critical exponents for the momentum and p osition fluctuations increase on the critical line. The quantum nature of the fluctuations in T = 0 is, however, preserved.