NONERGODICITY PARAMETERS FOR A MOLECULAR LIQUID - A COMPARISON BETWEEN MODE-COUPLING THEORY AND SIMULATION

We apply the mode coupling theory (MCT) which was recently applied to molecular liquids to a liquid of diatomic, rigid molecules. Making use of the static correlators, S-ll'(m)(q), from a molecular dynamical si mulation, we have solved the MCT equations for the non-ergodicity para meters (NEP), f(l)(m)(q) = lim(t-->infinity) S-ll(m)(q, t)/S-ll(m)(q), assuming that all correlators are non-zero for l = l' = 0, 1, ..., l( co), only. Depending on l(co) = 0, 1,2 we obtain different types of id eal glass transitions with transition temperatures, T-c((l)) which are , from a molecular dynamics (MD) simulation, below T-c(MD). The q-depe ndence of the critical NEP, (f(l)(m))(c)(MD), from the simulation is r easonably well reproduced by the corresponding MCT result. The affect of a strong and weak diagonalization approximation on the results is d iscussed. (C) 1998 Elsevier Science B.V. All rights reserved.