Gaussrate 17-B

Abstract: Gaussrate 17 is a set of Fortran subroutines and Unix scripts for interfacing the Polyrate and Gaussian 16 and / or 09 computer programs to one another for the purpose of carrying out direct dynamics calculations of gas-phase, liquid-phase, and solid–gas-interface chemical reaction rates of polyatomic species (and also atoms and diatoms as special cases) using the electronic structure methods available in Gaussian 09 to calculate the potential energy surface and Polyrate for the dynamics. The interface is based on the Polyrate hooks protocol. The dynamical methods used are (i) variational transion state theory based on a reaction path (or conventional transition state theory) and multidimensional semiclassical approximations for tunneling and nonclassical reflection and (ii) variable-reactioncoordinate variational transion state theory with single-faceted or multifaceted dividing surfaces. For reaction-path calculations, multistructural and multi-path variational transition state theory can be carried out with the MSTor code. Also for reaction-path calculations, liquid-phase computations can be carried out by turning on implicit solvation model in Gaussian (for instance, via the keyword SCRF=SMD). Rate constants may be calculated by any of the methods available in the Polyrate program for both tight and loose transition states.

Reactions involving tight transition states are treated by reaction-path variational transition state theory (RP-VTST). The methods are canonical variational transition state theory, microcanonical variational state theory, or conventional transition state theory with multidimensional semiclassical approximations for tunneling and nonclassical reflection. Bimolecular and unimolecular reactions are included. Both single-level and dual-level calculations may be carried out. In single-level mode, optimized geometries, potential energies, gradients, and Hessians can be calculated by any of the ab initio or semiempirical methods in the Gaussian 16 / 09 package. In dual-level mode, the lower-level data is calculated by Gaussian 16 / 09, and the higher-level data is read in from an external file.

The user needs to obtain the following packages:

From the University of Minnesota:

• Polyrate: Polyrate is a licensed code available from the University of Minnesota. Currently the license fee is waived for all users. For further information about Polyrate see https://comp.chem.umn.edu/polyrate.
• Gaussrate: Gaussrate is a licensed code available from the University of Minnesota. Currently the license fee is waived for all users. For further information about the Gaussrate code see https://comp.chem.umn.edu/gaussrate.

• Gaussian 16 / 09: Gaussian 16 and 09 are licensed codes available from Gaussian Inc. For further information see http://www.gaussian.com/. The prospective user of Gaussrate must obtain and install Gaussian 16 or Gaussian 09 before proceeding.