Dynamical model of the dielectric screening of conjugated polymers

TL;DR

This paper introduces a dynamical model for dielectric screening in conjugated polymers, using the density matrix renormalization group method, revealing significant exciton energy reduction and differential screening effects.

Contribution

It presents a novel dynamical model combining a line of quantized dipoles with the P-P-P model for polymers, analyzed via advanced computational methods.

Findings

Screened exciton binding energy reduced by about 1 eV

Covalent states are weakly screened compared to ionic states

Screening of excitons approaches the dispersion limit

Abstract

A dynamical model of the dielectric screening of conjugated polymers is introduced and solved using the density matrix renormalization group method. The model consists of a line of quantized dipoles interacting with a polymer chain. The polymer is modelled by the Pariser-Parr-Pople (P-P-P) model. It is found that: (1) Compared to isolated, unscreened single chains, the screened 1Bu- exciton binding energy is typically reduced by ca. 1 eV to just over 1 eV; (2) Covalent (magnon and bi-magnon) states are very weakly screened compared to ionic (exciton) states; (3) Screening of the 1Bu- exciton is closer to the dispersion than solvation limit.