TRACER DIFFUSION IN A SYSTEM WITH RANDOMLY DISTRIBUTED TRAPS .2.

An approximate theory for tracer diffusion on a lattice containing ran domly distributed traps and in the presence of a finite concentration of diffusing particles which preclude double occupancy of any site is developed by extending earlier theories of diffusion in a many-particl e system on perfect lattices using random-walk concepts. Both blocking and dynamic correlation effects are considered. The theoretical resul ts are compared with computer simulation for a two-dimensional square lattice with two types of trap over the entire concentration range for particles and traps. The agreement between the simulation results and the theory is satisfactory and gives confidence that the approximatio n will be valid more widely in models of diffusion in disordered latti ces.