Accelerating Instanton Theory with the Line Integral Nudged Elastic Band Method and Gaussian Process Regression.

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Quantum Mechanics

Background:

• Quantum tunneling is crucial for chemical reactions, especially proton transfer.
• Ring polymer instanton theory is a key computational tool for tunneling rates.
• On-the-fly electronic structure calculations with instanton methods are computationally intensive.

Purpose of the Study:

• To develop a more efficient computational method for calculating quantum tunneling rates.
• To combine the Line Integral Nudged Elastic Band (LI-NEB) with Gaussian Process Regression (GPR) for enhanced efficiency.
• To enable the study of proton transfer in larger and more complex molecular systems.

Main Methods:

• Implementation of a novel efficient ring polymer instanton method.
• Integration of the Line Integral Nudged Elastic Band (LI-NEB) approach.
• Application of Gaussian Process Regression (GPR) for potential energy surface generation.
• Benchmarking on ground-state proton transfer systems: H + CH4, malonaldehyde, and Z-3-amino-propenal.

Main Results:

• The combined LI-NEB and GPR method is an order of magnitude faster than traditional instanton algorithms.
• The new method achieves excellent agreement with existing tunneling rate calculations.
• Demonstrated efficiency and accuracy on benchmark proton transfer reactions.

Conclusions:

• The developed method offers a significant speed-up for quantum tunneling rate calculations.
• This approach facilitates the study of proton transfer in larger molecular systems.
• The LI-NEB/GPR combination represents a practical advancement in computational chemistry for reaction dynamics.