Optimized Effective Potential Method for Polymers

TL;DR

This paper applies the optimized effective potential (OEP) method with the KLI approximation to polymers, specifically polyethylene, to accurately compute electronic properties and band gaps, demonstrating the importance of basis set choice and exchange contributions.

Contribution

First application of the OEP method with KLI approximation to polymers, providing insights into band structure calculations and the role of exchange contributions in band gap accuracy.

Findings

Larger basis sets yield narrower band gaps.

Exchange contribution is crucial for correct band gap estimation.

OEP with KLI improves understanding of polymer electronic properties.

Abstract

The optimized effective potential (OEP) method allows for calculation of the local, effective single particle potential of density functional theory for explicitly orbital-dependent approximations to the exchange-correlation energy functional. In the present work the OEP method is used together with the approximation due to Krieger, Li and Iafrate (KLI). We present the first application of this method to polymers. KLI calculations have been performed for the insulating polyethylene and the results have been compared to those from other orbital-dependent potentials. Various properties of the band structure are also calculated. The single-particle band gap strongly depends on the basis set with larger basis sets yielding narrow gaps. For the highest occupied orbital energy the difference is more pronounced. In order to get the right band gap in OEP the exchange contribution to the derivative discontinuity is calculated and added to the Kohn-Sham gap.