Static and dynamic correlations in fluids with internal quantum states: Computer simulations and theory

Abstract

We continue our investigation of the properties of a model fluid whose molecules have classical translational degrees of freedom and two quantum internal states. The attractive pair interactions are ``turned on'' when the internal states are hybridized, corresponding to the molecules acquiring a ``dipole'' moment. The phase diagram of this system in the temperature-density plane as well as the static and imaginary-time correlations at various densities are investigated by Monte Carlo simulations, using the ``polymer'' representation, for different strengths of the quantum parameter. These are compared with low-density expansions and mean-field-theory predictions. Good agreement is found in appropriate regimes.