NEXMD v2.0 Software Package for Nonadiabatic Excited State Molecular Dynamics Simulations

Area of Science:

• Computational Chemistry
• Quantum Dynamics
• Molecular Modeling

Background:

• Accurate simulation of excited-state molecular dynamics is crucial for understanding photophysical processes.
• Existing methods like trajectory surface hopping (TSH) have limitations in capturing complex quantum effects.

Purpose of the Study:

• Introduce NEXMD version 2.0, featuring new hybrid quantum-classical dynamics methods.
• Compare the strengths and weaknesses of Ehrenfest dynamics (EHR), Ab-Initio Multiple Cloning (AIMC), and TSH within the NEXMD framework.
• Enhance the analysis of vibronic dynamics and quantum coherences in molecular systems.

Main Methods:

• Implementation of Ehrenfest dynamics (EHR) and Ab-Initio Multiple Cloning (AIMC) in NEXMD v2.0.
• Direct comparison of EHR, AIMC, and TSH using modeled photodynamics of a polyphenylene ethylene dendrimer.
• Expanded normal-mode analysis and constraints for ground and excited states.

Main Results:

• NEXMD v2.0 offers alternative hybrid quantum-classical dynamics methods (EHR, AIMC) to TSH.
• Comparative analysis highlights the strengths and weaknesses of each method for specific photodynamic scenarios.
• New analysis tools enable deeper investigation of vibrational motions and vibronic dynamics.

Conclusions:

• NEXMD v2.0 significantly expands the applicability of nonadiabatic excited-state molecular dynamics simulations.
• The software now better handles multichromophore organic molecules and complex photophysical processes.
• Improved methods facilitate the study of quantum coherences and state couplings in excited molecules.