Methods for analysing transport in disordered systems with long-range traps

The continuous time random walk (CTRW) methods and the homomorphic cluster coherent potential approximation (HCCPA) are known to be useful approximate methods for the analysis of transport between localised states in ordinary disordered systems. In order to examine their applicability to disordered systems in the presence of long-range traps, calculations of the trapping probability were performed by these methods for ordered systems containing such traps, and the results compared with those obtained by the usual coherent potential approximation. It is found that the HCCPA method is totally unreliable for such systems, and the reasons for this are discussed. The CTRW methods are found to be unreliable for quantitative results, but the results that they give have the correct qualitative behaviour.