Cluster effects on transition state dynamics are investigated through a time-dependent calculation of photodetachment spectrum of Ar(ClHCl)(-). This system is studied by propagating a three-dimensional grid representation of the wave function in the H atom coordinates, coupled to three one-dimensional semiclassical Gaussians in the three lowest frequency normal coordinates of Ar(ClHCl)(-). Over the 75 fs propagation times considered here, the motions of the three heavy atoms are very small. Therefore, we expect that the coupled quantum/semiclassical propagation will be in quantitative agreement with a full quantum treatment of this system. The couplings between the quantum and semiclassical degrees of freedom and between the three semiclassical degrees of freedom are introduced through the time-dependent self-consistent field (TDSCF) approximation. A computational bottleneck in applying the TDSCF approximation to such systems is that propagation of each of the modes requires the;evaluation of the average of the potential over the wave functions in the three remaining modes. A solution to this problem for H transfer systems is presented and discussed. Comparisons between the dynamics of Ar(CMCl) and ClHCl indicate that the presence of the Ar atom produces a hole in the wave function that is otherwise cylindrically symmetric. Possible observable experimental consequences of the introduction of the Ar atom to this system are discussed.