Nonadiabatic Excited-State Molecular Dynamics with an Explicit Solvent: NEXMD-SANDER Implementation

Abstract

In this article, the nonadiabatic excited-state Molecular dynamics (NEXMD) package is linked with the SANDERpackage, provided by AMBERTOOLS. The combination of these software packages enables the simulation of photoinduceddynamics of large multichromophoric conjugated molecules involving several coupled electronic excited states embedded in anexplicit solvent by using the quantum/mechanics/molecular mechanics (QM/MM) methodology. The fewest switches surfacehopping algorithm, as implemented in NEXMD, is used to account for quantum transitions among the adiabatic excited-statesimulations of the photoexcitation and subsequent nonadiabatic electronic transitions, and vibrational energy relaxation of asubstituted polyphenylenevinylene oligomer (PPV3-NO2) in vacuum and methanol as an explicit solvent has been used as a testcase. The impact of including specific solvent molecules in the QM region is also analyzed. Our NEXMD-SANDER QM/MMimplementation provides a useful computational tool to simulate qualitatively solvent-dependent effects, like electron transfer,stabilization of charge-separated excited states, and the role of solvent reorganization in the molecular optical properties, observed insolution-based spectroscopic experiments.