title: Mutual diffusion in a binary isotopic mixture.
abstract: The mass dependence of the mutual diffusion coefficient, in a binary equimolar mixture of Lennard-Jones fluids, is studied within Mori's memory function formalism. A phenomenological form of the memory function is used to study the time evolution of the self- and relative velocity correlation functions. The diffusion coefficients are calculated from the relevant velocity correlation functions using the Green-Kubo integral formula. Like the self-diffusion coefficient, the mutual diffusion coefficient is also found to be weakly dependent on the mass ratio. The present study shows that the minimum value that the mutual diffusion coefficient in an equimolar mixture of isotopic fluids can have is √(1/2) times the self-diffusion coefficient of any of the species when in isolation. Further, the contribution of the dynamic/distinct cross correlations to the mutual diffusion coefficient is found to be small and positive for the whole range of the mass ratio which is consistent with earlier molecular dynamics results.
authors.affiliation: Department of Physics, Himachal Pradesh University, Shimla-171005, India. sramanb70@mailcity.com
authors.forename: Raman
authors.initials: R
authors.lastname: Sharma
authors.forename: K
authors.initials: K
authors.lastname: Tankeshwar
mesh_terms: D016880:Anisotropy; D045424:Complex Mixtures / Q000737:chemistry*; D003198:Computer Simulation; D004058:Diffusion; D008956:Models, Chemical
chemical_list: D045424:Complex Mixtures