Knowledge Bank

Based on recent {\textit {ab initio}} results,}} {\textbf {110,}} 10345, (2006) and R. A. DiStasio Jr., G. von Helden, R. P. Steele, and M. Head-Gordon {\textit {Chem. Phys. Lett.}} (2007), doi: 10.1016/j.cplett.2007.02.034.} the benzene dimer is predicted to have a distorted $alT$-shaped equilibrium structure; one benzene ring forming the stem'' of the $alT$'' and the other forming the ``cap.'' The barriers for several tunneling pathways, such as stem-bending, cap-torsion and stem-torsion, have been calculated. In this talk the energy splitting patterns, and nuclear spin statistical weights, that characterize such tunneling pathways will be discussed. Comparison with high resolution spectra will be made for (C$6$H$6$)$2$, (C$6$D$6$)$2$, and C$6$H$6$-C$6$D$6$.