Electronic structure of solid coronene: differences and commonalities to picene

TL;DR

This paper presents the first-principles electronic structure analysis of solid coronene, comparing it to picene, to understand their similarities and differences as aromatic superconductors, especially upon potassium doping.

Contribution

It provides the first detailed electronic structure comparison between coronene and picene, highlighting their band structures, Fermi surfaces, and effects of potassium doping.

Findings

Coronene's conduction bands originate from molecular orbitals similar to picene.

Doped coronene exhibits a multi-sheet Fermi surface with high anisotropy.

Electronic structures show entanglement of bands as in picene.

Abstract

We have obtained the first-principles electronic structure of solid coronene, which has been recently discovered to exhibit superconductivity with potassium doping. Since coronene, along with picene, the first aromatic superconductor, now provide a class of superconductors as solids of aromatic compounds, here we compare the two cases in examining the electronic structures. In the undoped coronene crystal, where the molecules are arranged in a herringbone structure with two molecules in a unit cell, the conduction band above an insulating gap is found to comprise four bands, which basically originate from the lowest two unoccupied molecular orbitals (doubly-degenerate, reflecting the high symmetry of the molecular shape) in an isolated molecule but the bands are entangled as in solid picene. The Fermi surface for a candidate of the structure of K$_x$coronene with $x=3$, for which superconductivity is found, comprises multiple sheets, as in doped picene but exhibiting a larger anisotropy with different topology.