Non-ergodicity parameters for a molecular liquid: a comparison between mode coupling theory and simulation

Abstract

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 simulation, we have solved the MCT equations for the non-ergodicity parameters (NEP), f l m(q)= lim t→∞ 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 ideal glass transitions with transition temperatures, T ( l) c which are, from a molecular dynamics (MD) simulation, below T MD c. The q-dependence of the critical NEP, ( f l m ) c MD, from the simulation is reasonably well reproduced by the corresponding MCT result. The affect of a strong and weak diagonalization approximation on the results is discussed.