Professor Edwin L. Sibert at the Department of Chemistry, the University of Wisconsin at Madison, is supported by a grant from the Theoretical and Computational Chemistry Program at NSF for the theoretical analysis of vibration/rotation dynamics of polyatomic molecules in the gas phase. The quantum mechanical studies which Prof. Sibert is undertaking are in three areas. The first area focuses on highly excited states where assignment of states is difficult due to a high degree of mixing of different rotational and vibrational levels. The problems due to this mixing are avoided by investigation of properties of ensembles rather than the study of individual states. The other two projects are devoted to describing spectroscopy and dynamics at transition states of chemical reactions. The research which is being carried out under this grant is valuable for the interpretation and assignment of molecular spectra. Further, the understanding that is being given by the research on the behavior near transition states of reactions is essential to obtain reaction rates and to accurately predict the distributions of reaction products.