| The dynamical properties of spin systems are very important in the field of phase transitions and critical phenomena. Recently, the study of the random quantum spin systems attracts lots of attention of many researchers. In this thesis, the effects of disorder on the dynamics of the two-dimensional random quantum Ising system are studied, and the main results are as follows:The effects of disorder on the dynamics of the two-dimensional isotropic Ising model are investigated when the nearest-neighbor exchange couplings (or the external transverse fields) satisfy the bimodal distribution. Autocorrelation functions and corresponding spectral densities of the system are obtained by the recurrence relation method. The results show that the dynamics of the system changes according to the concentrations of the nearest-neighbor exchange coupling J and the transverse field B, i.e., when J>B, the spin correlation functions show monotonically decreasing,and the dynamics of system is dominated by the central peak behavior. While forJ |
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