MONTE-CARLO SIMULATIONS OF THE FIRST-ORDER PHASE-TRANSITION IN VANADIUM DIOXIDE

Monte Carlo techniques previously applied to modelling nucleation proc esses by van Duijneveldt and Frenkel in 1992, have been used to invest igate a first-order phase transition of vanadium dioxide which occurs at 340 K. A low-symmetry monoclinic distorted rutile phase transforms to a tetragonal rutile-type structure. Interionic potentials have been derived from a periodic Hartree-Fock study of this transition: which reproduce the structural parameters of the two phases to within 4%. No n-Boltzmann-weighted Monte Carlo simulations showed that a small free- energy barrier (of the order of kT), separates the distorted structure from the more thermodynamically stable phase.