"Transitivity": A Code for Computing Kinetic and Related Parameters in Chemical Transformations and Transport...

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Chemical Kinetics

Background:

• The Arrhenius law is a cornerstone of chemical kinetics but has limitations at low temperatures.
• Understanding reaction propensity and implementing phenomenological kinetic models requires accurate parameter estimation.
• Deviations from Arrhenius behavior at low temperatures necessitate advanced analytical tools.

Purpose of the Study:

• To introduce the Transitivity code, a user-friendly graphical interface for estimating kinetic and thermodynamic parameters.
• To provide a tool for evaluating the temperature dependence of rate constants using Arrhenius and Transitivity plots.
• To facilitate the study of non-Arrhenius behavior at low temperatures, a critical area of current research.

Main Methods:

• Development of a Python-based, open-source code named Transitivity.
• Implementation of the Transitivity function to measure reaction propensity.
• Integration of Transition-State Theory with various tunneling corrections (Bell, Skodje, Truhlar, d-TST).
• Inclusion of Kramers and Collins-Kimball formulations to account for solvent effects.
• Provision of an input file generator for molecular dynamics simulations (CPMD).

Main Results:

• The Transitivity code offers a graphical interface for analyzing kinetic and thermodynamic parameters.
• It enables evaluation of rate constant temperature dependence via Arrhenius and Transitivity plots.
• The code effectively utilizes deformed Transition-State Theory (d-TST) formulations to address non-Arrhenius behavior.
• It supports calculations incorporating solvent effects and molecular dynamics inputs.

Conclusions:

• The Transitivity code is a versatile, cross-platform tool for kinetic and thermodynamic analysis.
• Its strength lies in its ability to handle non-Arrhenius behavior at low temperatures using d-TST.
• The code serves as a practical tool for data documentation from electronic structure calculations and as educational courseware.