TheRate: Program forab initio direct dynamics calculations of thermal and vibrational-state-selected rate constants

Abstract

We introduce TheRate (THEoretical RATEs), a complete application program with a graphical user interface (GUI) for calculating rate constants from first principles. It is based on canonical variational transition‐state theory (CVT) augmented by multidimensional semiclassical zero and small curvature tunneling approximations. Conventional transition‐state theory (TST) with one‐dimensional Wigner or Eckart tunneling corrections is also available. Potential energy information needed for the rate calculations are obtained from ab initio molecular orbital and/or density functional electronic structure theory. Vibrational‐state‐selected rate constants may be calculated using a diabetic model. TheRate also introduces several technical advancements, namely the focusing technique and energy interpolation procedure. The focusing technique minimizes the number of Hessian calculations required by distributing more Hessian grid points in regions that are critical to the CVT and tunneling calculations and fewer Hessian grid points elsewhere. The energy interpolation procedure allows the use of a computationally less demanding electronic structure theory such as DFT to calculate the Hessians and geometries, while the energetics can be improved by performing a small number of single‐point energy calculations along the MEP at a more accurate level of theory. The CH4+H↔CH3+H2 reaction is used as a model to demonstrate usage of the program, and the convergence of the rate constants with respect to the number of electronic structure calculations. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1039–1052, 1998

Single water-molecule catalysis in the glyoxal + OH reaction under tropospheric conditions: Fact or fiction? A quantum chemistry and pseudo-second order computational kinetic study

“…The rate coefficients (k) are computed using conventional Transition State Theory (TST) [16][17][18] as implemented in TheRate program [19] at the Computational Science and Engineering Online website (www.cseo.net) [20]. Tunneling corrections are taken into account, assuming unsymmetrical Eckart [21] barriers.…”

Kinetics of the Hydrogen Abstraction •CH3 + Alkane → CH4 + Alkyl Reaction Class: An Application of the Reaction Class Transition State Theory

“…To derive the RC-TST correlation functions, TST/Eckart rate constants for all reactions in the above representative reaction set were calculated by employing the TheRate program [34]. In these calculations, overall rotations were treated classically, and vibrations were treated quantum mechanically within the harmonic approximation except for the modes corresponding to the internal rotations of the -CH 3 groups, which were treated as the hindered rotations (HRs) using the method suggested by Ayala et al [35].…”

KiSThelP: A program to predict thermodynamic properties and rate constants from quantum chemistry results†

“…To calculate the pressure and temperature dependence of an unimolecular process by using RRKM theory and a numerical solution of the master equation for multiple reaction channels is the main objective of some of these programs, such as MultiWell, [2][3][4] MesMer, [31] UNIMOL, [32] VariFlex, [33] and ChemRate. [34] Other programs, mainly centred on the use of the TST, such as POLYRATE [1] and TheRate, [35] focus only on the temperature dependence of canonical rate constants (at high-limit pressure) but for unimolecular and bimolecular reactions. In this case, much of the effort is devoted to describe as accurately as possible quantum mechanical effects on reaction coordinate motion, using multidimensional tunnelling corrections, and to account more accurately for recrossing effects.…”