Tight-Binding Parametrization of First-Principles Electronic Dispersion in Orientationally Disordered A3c60

TL;DR

This paper develops a numerical tight-binding model for the electronic dispersion in disordered A3C60 phases, derived from first-principles calculations, to better understand the effects of orientational disorder.

Contribution

The authors introduce a new set of tight-binding parameters obtained via Fourier inversion from first-principles spectra, accounting for orientational dependence in A3C60.

Findings

Validated some previous orientational ordering results

Modified some earlier conclusions about electronic dispersion

Provided a versatile parametrization for disordered phases

Abstract

We derive numerical tight-binding hopping parameters to describe conduction-band dispersion in arbitrary orientational phases of $A_3$C$_{60}$. The parameters are obtained by direct Fourier inversion of the spectra from self-consistent electronic-structure calculations for K$_3$C$_{60}$ using the local-density approximation, including the effects of orientational dependence. Using the new parameters, we revisit several earlier investigations of the orientational ordering in $A_3$C$_{60}$; some of the earlier results are substantiated, while others are slightly modified.