Over the past few years, we have been developing efficient software frameworks designed to simulate non-equilibrium chemical reaction dynamics. These methods utilize an MPI-parallelized linear-scaling computational framework developed to implement arbitrarily large multi-state empirical valence bond (MS-EVB) calculations within commonly used molecular dynamics packages, including both CHARMM and TINKER. Forces are obtained using the Hellmann-Feynman relationship, giving continuous gradients, and good energy conservation. Utilizing multi-dimensional Gaussian coupling elements fit to electronic structure theory results (including explicitly correlated coupled cluster theory), we are able to build reactive potential energy surfaces whose balanced accuracy and efficiency considerably surpass what we could achieve otherwise. These methods have found application in atomistic studies of fundamental chemical reaction dynamics occurring in liquids, and have shed light on a number of interesting chemical phenomena, including: (a) vibrational energy deposition in typical organic solvents; (b) ultrafast energy flow and transient spectroscopy in the immediate aftermath of a chemical reaction, and (c) the interplay between microsolvation dynamics and chemical reaction dynamics.
In this talk, I will briefly outline some of the recent applications that we have tackled using this framework. I will also provide a guided demonstration of how to use the MS-EVB enabled version of TINKER which we have been developing. I will walk the audience through a short example, showing how to compile the MPI-parallelized version of TINKER, and then set up and simulate a simple chemical reaction.
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