Software Development for Integrating Molpro with Newton-X for Adiabatic and Non-adiabatic Excited State Dynamics

Abstract

An interface between the non-adiabatic dynamics software Newton-X and the quantum chemistry software package Molpro has been created for select methods: second order local coupled cluster (LCC2), second order local algebraic diagrammatic construction (LADC(2)), and complete active space self-consistent field (CASSCF). This interface incorporates Molpro electronic structure methods for the generation of absorption spectra, adiabatic dynamics, and non-adiabatic dynamics via surface hopping. Functionality of the interface was tested with (i) absorption spectra generation using LCC2 and LADC(2) sampling of a Wigner distribution of the ground state for thiophene and the B-Te-6-B tellurophene, (ii) absorption spectra for thiophene using CASSCF, and (iii) non-adiabatic dynamics for methaniminium and thiophene using CASSCF. For the LCC2/LADC(2) integration, CAM-B3LYP/cc-pVDZ optimized geometries and normal modes were used as the initial seed for the ensemble of Wigner distribution sampled geometries. These sampled geometries were then processed with LCC2/LADC(2) to generate UV-Vis absorbance spectra for the two aforementioned molecules: thiophene and B-Te-6-B. Spectra generated compare reasonably well with experimentally measured spectra, although there are blue-shifts possibly due to the use of modest-sized basis sets for computational efficiency. There are also discrepancies in peak intensities for B-Te-6-B but these could be accounted for by incorporating more excited states, at increased computational cost. Simulations using the integration of Molpro for CASSCF dynamics were successful in replicating literature results for a methaniminium trajectory and of a thiophene ring opening involving a non-adiabatic transition from the first excited state to the ground state. This CASSCF implementation also permits UV-Vis spectrum generation via sampling a ground state Wigner distribution and adiabatic dynamics, where trajectories are propagated on a single potential energy surface.