Getting excited: Challenges in quantum-classical studies of excitons in polymeric systems

TL;DR

This paper combines classical molecular dynamics and quantum chemical calculations to study excitons in polymeric systems, assessing the reliability of excitation energies derived from different conformational models.

Contribution

It develops a methodology integrating MM/MD and DFT to accurately predict optical excitations in polymeric systems, enhancing computational efficiency.

Findings

Good agreement between MM/MD and DFT conformations for excitation energies

Validated the use of MM/MD conformations for optical property calculations

Improved force field parameters for DPE, methylated-DPE, and PPE

Abstract

A combination of classical molecular dynamics (MM/MD) and quantum chemical calculations based on the density functional theory (DFT) was performed to describe conformational properties of diphenylethyne (DPE), methylated-DPE and poly para phenylene ethynylene (PPE). DFT calculations were employed to improve and develop force field parameters for MM/MD simulations. Many-body Green's functions theory within the GW approximation and the Bethe-Salpeter equation were utilized to describe excited states of the systems. Reliability of the excitation energies based on the MM/MD conformations was examined and compared to the excitation energies from DFT conformations. The results show an overall agreement between the optical excitations based on MM/MD conformations and DFT conformations. This allows for calculation of excitation energies based on MM/MD conformations.