INTERPOLATED VARIATIONAL TRANSITION-STATE THEORY BY MAPPING

We present a new systematic set of algorithms for interpolated variati onal transition-state theory by mapping (IVTST-M). In this method, whi ch is designed to allow efficient direct dynamics calculations, rate c onstants for chemical reactions are evaluated by variational transitio n-state theory with multidimensional tunneling approximations based on reaction-path data. The data (energies, energy gradients, and Hessian s) are computed at a small number of points along a reaction path and Fitted to splints under tension as functions of a mapped independent v ariable that is a nonlinear function of the reaction coordinate. The t heory is illustrated and tested by several examples, and standard choi ces are employed for all parameters and functional forms to provide a realistic test of how the method might perform when applied as an auto matic scheme without fine-tuning each reaction. For eight test cases, we obtain reasonable accuracy (as compared to calculations with the sa me potential surface with the reaction path followed as far as necessa ry for convergence) with Hessians at only six nonstationary points.