Polarons and charge carrier solvation on conjugated carbon chains: A comparative ab initio study

TL;DR

This study investigates how excess charge carriers localize on long conjugated carbon chains, considering lattice displacements and solvent effects, comparing different computational methods to understand the polaron formation.

Contribution

It provides a comparative ab initio analysis of polaron formation on conjugated chains, highlighting the role of solvation and different computational approaches.

Findings

Solvation promotes charge localization.

Different computational methods yield distinct localization patterns.

Lattice displacements correlate with charge and spin densities.

Abstract

We study accommodation of an excess charge carrier on long even-N polyynic oligomers C_{N}H_{2} due to displacements of the underlying carbon lattice and polarization of the surrounding solvent in the context of carrier self-localization into a polaronic state. Spatial patterns of bond-length alternation, excess charge and spin densities are compared as derived with Hartree-Fock and two hybrid-DFT methods (BHandHLYP and B3LYP) in conjunction with the polarizable continuum model. Quite distinct resulting pictures of carrier accommodation are found when contributions from different interactions are analyzed. Solvation robustly acts to promote excess charge localization.