An analysis and extension of the continuous time random walk method. II. The AC conductivity of some model disordered one-dimensional systems

In order to test the accuracy of the usual continuous time random walk (CTRW) method, calculations were performed using it and its extension, the CTRW(n) method, for two types of one-dimensional disordered system. For the first of these, which corresponds to direct hopping between localised states of similar energy, the usual CTRW method was found to be qualitatively correct, but quantitatively unreliable because of its neglect of correlation between successive transitions. For the second type of system, which corresponds to band transport with multiple trapping, the usual CTRW method was found to be quite accurate.