Nonadiabatic Excited State Molecular Dynamics with explicit solvent: NEXMD-SANDER implementation

In this article, the Nonadiabatic Excited-state Molecular dynamics (NEXMD) package is linked with the SANDER package, provided by AMBERTOOLS. The combination of these software packages enables the simulation of photoinduced dynamics of large multichromophoric conjugated molecules involving several coupled electronic excited states embedded in an explicit solvent by using Quantum/Mechanics/Molecular Mechanics (QM/MM) methodology. The fewest switches surface hopping algorithm, as implemented in NEXMD, is used to account for quantum transitions among the adiabatic excited-states Simulations of the photoexcitation and subsequent nonadiabatic electronic transitions and vibrational energy relaxation of a substituted polyphenylene vinylene oligomer (PPV3-NO2) in vacuum and methanol as explicit solvent has been used as a test case. The impact of including specific solvent molecules in the QM region is also analysed. Our NEXMD-SANDER QM/MM implementation provides a useful computational tool to simulate qualitatively solvent-dependent effects, like electron transfer, stabilization of charge separated excited states, the role of solvent reorganization in the molecular optical properties, observed in solution-based spectroscopic experiments.