Self-consistent variational transition state theory with multidimensional tunneling calculations in an embarrassingly parallel scheme

Variational Transition State Theory with Multidimensional Tunneling (VTST/MT) has been successfully used for calculating rate constants of reactions in gas and condensed phases. The current software implementation of VTST/MT is, however, based on the assumption of a fast, serial evaluation of the energetic information of a given molecular structure. We propose a simple and effective parallel method for performing VTST/MT calculations utilizing a cost effective Linux based PC cluster. Five different parallel computing schemes for choosing structures and computing their Hessians along a pre-defined Minimum Energy Path were developed. We found that the Energy Block and Asymmetric Cyclic Execution (EBACE) scheme, which is also most physically intuitive, results in converged rate constants with the least number of Hessians computed. We believe that carrying out the VTST/MT calculation in parallel makes it more attractive for calculating the rate constants of complex chemical systems.