Energy conservation in real-time nuclear-electronic orbital Ehrenfest dynamics

Area of Science:

• Quantum chemistry
• Theoretical chemistry
• Computational chemistry

Background:

• Real-time nuclear-electronic orbital Ehrenfest (RT-NEO-Ehrenfest) dynamics methods enable first-principles simulation of nonadiabatic molecular processes.
• The traveling proton basis (TPB) approach enhances RT-NEO-Ehrenfest dynamics for proton transfer by allowing quantum proton basis functions to move classically.
• Existing TPB methods show limitations in conserving system energy during simulations.

Purpose of the Study:

• To develop an improved TPB approach for RT-NEO-Ehrenfest dynamics that enhances system energy conservation.
• To accurately capture quantum proton dynamics in nonadiabatic processes.
• To address the energy conservation shortcomings of previous TPB methods.

Main Methods:

• Proposed a thermostatted TPB approach for RT-NEO-Ehrenfest dynamics.
• Dynamically rescaled the proton momentum operator to maintain system energy conservation.
• Applied the method to simulate excited-state intramolecular proton transfer in o-hydroxybenzaldehyde.

Main Results:

• The thermostatted TPB approach significantly improved system energy conservation.
• The method preserved the accuracy of quantum proton dynamics compared to original TPB approaches.
• Demonstrated successful application to a model system (o-hydroxybenzaldehyde).

Conclusions:

• The proposed thermostatted TPB approach offers a more reliable method for simulating quantum proton transfer within RT-NEO-Ehrenfest dynamics.
• This advancement leads to more accurate and stable simulations of nonadiabatic molecular processes.
• The method provides a robust tool for studying quantum effects in chemical reactions.