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

We present NEXMD version 2.0, thesecond release of the NEXMD (NonadiabaticEXcited-state Molecular Dynamics) software package. Across a varietyof new features, NEXMD v2.0 incorporates new implementations of twohybrid quantum-classical dynamics methods, namely, Ehrenfest dynamics(EHR) and the Ab-Initio Multiple Cloning sampling technique for MulticonfigurationalEhrenfest quantum dynamics (MCE-AIMC or simply AIMC), which are alternativeoptions to the previously implemented trajectory surface hopping (TSH)method. To illustrate these methodologies, we outline a direct comparisonof these three hybrid quantum-classical dynamics methods as implementedin the same NEXMD framework, discussing their weaknesses and strengths,using the modeled photodynamics of a polyphenylene ethylene dendrimerbuilding block as a representative example. We also describe the expandednormal-mode analysis and constraints for both the ground and excitedstates, newly implemented in the NEXMD v2.0 framework, which allowfor a deeper analysis of the main vibrational motions involved invibronic dynamics. Overall, NEXMD v2.0 expands the range of applicationsof NEXMD to a larger variety of multichromophore organic moleculesand photophysical processes involving quantum coherences and persistentcouplings between electronic excited states and nuclear velocity.