Path optimization by a variational reaction coordinate method. II. Improved computational efficiency through internal...

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Reaction Dynamics

Background:

• Traditional reaction path optimization often involves locating transition states and following paths downhill.
• Chain-of-states methods like nudged elastic band and string method are standard practices.
• The Variational Reaction Coordinate (VRC) method offers an alternative approach to reaction path optimization.

Purpose of the Study:

• To describe methods for incorporating redundant internal coordinates and potential energy surface interpolation into the VRC method.
• To reduce the per-iteration computational cost of the VRC method while maintaining its algorithmic efficiency.

Main Methods:

• The VRC method represents reaction paths using a linear expansion of continuous basis functions.
• Path optimization is achieved by minimizing the Variational Reaction Energy (VRE), the line integral of the potential energy gradient norm.
• Incorporation of redundant internal coordinates and potential energy surface interpolation are key methodological advancements.

Main Results:

• The VRC method, with constraints, can determine approximate reaction paths and converged geometries of transition states/intermediates in few iterations.
• The described methods reduce the number of potential energy surface evaluations required per iteration.
• High algorithmic efficiency of the VRC method is preserved with the new implementation.

Conclusions:

• The enhanced VRC method offers a computationally efficient approach for reaction path optimization.
• These improvements make the VRC method more practical for complex chemical systems.
• Further development can accelerate the study of chemical reaction mechanisms.