Optimizing the performance of the multiconfiguration mechanics method

The multiconfiguration molecular mechanics (MCMM) method is studied by carrying out calculations of reaction rate constants using variational transition state theory with optimized multidimensional tunneling. It is seen that the MCMM method with as little as one electronic structure Hessian can described the dynamically important regions of the ground-electronic state PES, including the corner-cutting tunneling region of the reaction swath, with practical accuracy.