Simple and efficient LCAO basis sets for the diffuse states in carbon nanostructures

TL;DR

This paper introduces a minimal LCAO basis set enhancement for accurately describing diffuse unoccupied states in carbon nanostructures within DFT calculations, simplifying and reducing computational complexity.

Contribution

It proposes a novel minimal basis set extension using long-range Bessel functions to efficiently capture diffuse states in carbon nanostructures.

Findings

Accurately describes diffuse states with minimal basis size

Retains simplicity compared to standard PAOs

Effective for both planar and curved carbon structures

Abstract

We present a simple way to describe the lowest unoccupied diffuse states in carbon nanostructures in density functional theory (DFT) calculations using a minimal LCAO (linear combination of atomic orbitals) basis set. By comparing plane wave basis calculations, we show how these states can be captured by adding long-range orbitals to the standard LCAO basis sets for the extreme cases of planar <it>sp2</it> (graphene) and curved carbon (C60). In particular, using Bessel functions with a long range as additional basis functions retain a minimal basis size. This provides a smaller and simpler atom-centered basis set compared to the standard pseudo-atomic orbitals (PAOs) with multiple polarization orbitals or by adding non-atom-centered states to the basis.