EFFECT OF FLUCTUATIONS ON THE FREEZING OF A COLLOIDAL SUSPENSION IN AN EXTERNAL PERIODIC POTENTIAL

We incorporate the effects of fluctuations in a density functional ana lysis of the freezing of a colloidal liquid in the presence of an exte rnal potential generated by interfering laser beams. A mean-field trea tment, using a density functional theory, predicts that with the incre ase in the strength of the modulating potential, the freezing transiti on changes from a first order to a continuous one via a tricritical po int for a suitable choice of the modulating wavevectors. We demonstrat e here that the continuous nature of the freezing transition at large values of the external potential V-e survives the presence of fluctuat ions. We also show that fluctuations tend to stabilize the liquid phas e in the large V-e regime.