A study of the condensed phases and solid-solid phase transition in toluene: A Monte Carlo investigation

A Monte Carlo study of the orthorhombic(beta), monoclinic(alpha), and liqui d phases of toluene in the isobaric isothermal ensemble employing variable shape simulation cell is reported here. The intermolecular potential of Wil liams and Starr is seen to reproduce the lattice parameters and other known properties reasonably well for the alpha -phase. The beta -phase is not re produced as well. The structure has been characterized in terms of the radi al distribution functions and orientational correlation functions. The tran sition from the orthorhombic low temperature beta -phase to the high temper ature monoclinic alpha -phase has been successfully simulated. The transiti on is first order and lies between 140 and 145 K in agreement with experime nt. The reverse transition from the alpha- to the beta -phase does not take place in agreement with experiment. The liquid phase density and the heat of vaporization are reproduced well. The potential employed predicts an int eraction energy which is about 5% in excess of the experimental value. The orientational correlation function and the radial distribution functions ar e sensitive to the potential and suggest where improvements are possible. ( C) 2000 American Institute of Physics. [S0021-9606(00)51742-5].