Parallel Implementation of Semiclassical Transition State Theory.

Area of Science:

• Computational Chemistry
• Chemical Kinetics
• Theoretical Chemistry

Background:

• Semiclassical Transition State Theory (SCTST) is crucial for accurate reaction rate calculations.
• Previous methods were limited in handling complex molecular systems with many degrees of freedom.
• Anharmonic effects and multidimensional tunneling are critical for precise kinetics modeling.

Purpose of the Study:

• To present parsctst, an efficient parallel implementation of SCTST.
• To enable the calculation of reaction rates for larger, more complex molecular systems.
• To incorporate multidimensional tunneling effects into SCTST calculations.

Main Methods:

• Developed parsctst based on prior work for vibrational density of states.
• Implemented parallel processing for enhanced computational efficiency.
• Applied the code to a proton transfer isomerization reaction.

Main Results:

• Parsctst efficiently handles over 100 coupled anharmonic vibrational degrees of freedom.
• The code accurately estimates reaction rate constants, including multidimensional tunneling.
• Demonstrated significant computational time savings compared to serial calculations.

Conclusions:

• Parsctst is a user-friendly tool for accurate kinetics modeling.
• The code facilitates the application of SCTST for larger systems in various chemical fields.
• Parsctst can serve as a valuable alternative to basic transition state theory for complex reactions.