This paper presents a continuation of our previous theoretical studies on the rate of isomerization of trans-stilbene from the first excited electronic state based on the potential energy surface of Vachev et al. [J. Phys. Chem. 99, 5247 (1995)]. Harmonic RRKM computations and molecular dynamics and Monte Carlo based classical rates are presented for deuterated isotopes of stilbene as well as hexane clusters of stilbene of varying size. Good agreement with experiment is found for energy dependent rates of d(12) vs h(12) stilbene. However, we find that the rate for d(2) stilbene is greater than for d(10) stilbene in contradiction to the experimental observations. For the hexane clusters we find that addition of hexane molecules causes a systematic decrease in the rate, in agreement with experiment. (C) 1997 American Institute of Physics.