The vibrations of benzene, studied by `Multimodeʹ

The variational normal coordinate code `Multimodeʹ has been used to predict the zero point, fundamentals and overtones of the 30-mode system, benzene. One through 4-mode integration coupling has been included. Vibrational self-consistent field and configuration interaction results have been obtained; they are compared with those of perturbation theory. These calculations demonstrate that `Multimodeʹ can be used to study the vibrational motion of larger molecules; furthermore we have shown that the degree of coupling can be used to predict the convergence of the vibrational levels.