Limits of validity for a semiclassical mean-field two-fluid model for Bose-Einstein condensation thermodynamics

We reinvestigate the Bose-Einstein condensation (BEC) thermodynamics of a w eakly interacting dilute Bose gas under the action of a trap using a semi-c lassical two-fluid mean-field model in order to find the domain of applicab ility of the model. Such a model is expected to break down once the conditi on of diluteness and weak interaction is violated. We find that this breakd own happens for values of coupling and density near the present experimenta l scenario of BEG. With the increase of the interaction coupling and densit y the model may lead to unphysical results for thermodynamic observables. ( C) 2000 Published by Elsevier Science B.V, All rights reserved.