Role of Conduction Electrons in the ortho-KC$_{60}$ Polymer

TL;DR

This study uses first-principles calculations to analyze the electronic structure and bonding in the orthorhombic K$_1$C$_{60}$ polymer, revealing three-dimensional inter-fullerene bonding and the effects of ring formation on conduction bands.

Contribution

It provides the first detailed computational analysis of the electronic structure and bonding mechanisms in the orthorhombic K$_1$C$_{60}$ polymer, highlighting the role of conduction electrons.

Findings

Identification of 3D inter-fullerene bonding involving $t_{1u}$ orbitals.

Ring formation lifts the $p_x$ band, affecting electronic properties.

Asymmetry between $p_x$ and $p_y$ influences chain binding and configuration.

Abstract

We present first-principles band calculations as well as structural optimization of the orthorhombic K$_1$C$_{60}$ polymerized phase. We found three-dimensional inter-fullerene bonding/anti-bonding characters consisting of $t_{1u}$ molecular orbitals with $p$-like symmetry in the conduction bands. The formation of the four-membered ring connecting the fullerenes lifts the $p_x$ band from the continuous $p_y$-$p_z$ band, where the z-axis is parallel to the chain. The asymmetry between $p_x$ and $p_y$ may play an important role in binding the chains with the rotational configuration proposed by Stephens et al.