Electronic Structure of Copper Phthalocyanine: a Comparative Density Functional Theory Study

TL;DR

This study systematically compares various density functional theory methods to analyze the electronic structure of copper phthalocyanine, highlighting the limitations of semi-local functionals and proposing a hybrid functional as a better choice.

Contribution

It provides a comparative analysis of DFT functionals for CuPc and recommends the HSE hybrid functional for accurate interface studies.

Findings

Semi-local functionals fail qualitatively for CuPc due to self-interaction errors.

Hybrid functionals, especially HSE, offer improved accuracy for CuPc electronic structure.

The study guides functional choice for CuPc/metal interface research.

Abstract

We present a systematic density functional theory study of the electronic structure of copper phthalocyanine (CuPc), using several different (semi)-local and hybrid functionals, and compare the results to experimental photoemission data. We show that semi-local functionals fail qualitatively for CuPc, primarily because of under-binding of localized orbitals due to self-interaction errors. We discuss an appropriate choice of functional for studies of CuPc/metal interfaces and suggest the Heyd-Scuseria-Ernzerhof screened hybrid functional as a suitable compromise functional.