Photoinduced Dynamics with Constrained Vibrational Motion: FrozeNM Algorithm.

Area of Science:

• Computational chemistry
• Molecular dynamics
• Quantum chemistry

Background:

• Ab initio molecular dynamics (AIMD) simulations are crucial for studying molecular motions and electronic-nuclear coupling.
• Identifying the specific vibrations influencing a process is key to understanding complex dynamics.

Purpose of the Study:

• To introduce FrozeNM, a novel algorithm for applying normal-mode constraints in AIMD simulations.
• To analyze the impact of vibrational normal-mode constraints on photoinduced energy transfer.

Main Methods:

• Implementation of the FrozeNM algorithm within a nonadiabatic excited state molecular dynamics code.
• Performing AIMD simulations with selective freezing of vibrational normal modes.
• Analysis of electronic relaxation and nonadiabatic coupling under modal constraints.

Main Results:

• Freezing a small subset of active normal modes significantly slows electronic relaxation.
• Normal-mode constraints reduce nonadiabatic coupling between electronic excited states.
• Validation of reduced dimensionality models by freezing non-essential vibrations.

Conclusions:

• FrozeNM is a valuable tool for investigating the role of vibrations in chemical and physical processes.
• The algorithm facilitates the development of simplified models capturing essential phenomena.
• Selective modal constraints offer insights into energy transfer dynamics in complex systems.