Analytic energy gradient of excited electronic state within TDDFT/MMpol framework: Benchmark tests and parallel...

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Molecular Dynamics

Background:

• Time-dependent density functional theory (TDDFT) is widely used for excited-state calculations.
• Hybrid Quantum Mechanics/Molecular Mechanics (QM/MM) models efficiently describe molecules in condensed phases.
• Accurate excited-state properties require accounting for environmental polarization effects.

Purpose of the Study:

• To extend TDDFT/MM methods by incorporating mutual polarization effects between QM and MM regions.
• To develop and implement a polarizable TDDFT/MM (TDDFT/MMpol) model.
• To assess the impact of environmental polarization on excited-state properties.

Main Methods:

• Implementation of a polarizable TDDFT/MM model within the Q-Chem/CHARMM interface.
• Inclusion of both linear response and state-specific features for polarization.
• Utilizing analytic excited-state energy gradients and Hessians for geometric optimization.

Main Results:

• Successful implementation of the TDDFT/MMpol model.
• Demonstration of the model's ability to capture mutual polarization effects.
• Validation through benchmark tests and preliminary applications, showing improved accuracy.

Conclusions:

• The developed TDDFT/MMpol model accurately describes excited-state properties by accounting for mutual polarization.
• This method is crucial for systems with significant photoexcitation-induced charge rearrangement.
• The parallel implementation ensures computational efficiency for complex molecular systems.