Accurate hyperfine couplings for C59N

TL;DR

This paper improves the accuracy of hyperfine coupling calculations in C59N by employing the Projector Augmented Wave method, addressing limitations of traditional basis sets in quantum chemistry.

Contribution

It introduces a novel application of the PAW method to compute hyperfine couplings in azafullerene, surpassing the accuracy of standard ab initio methods.

Findings

More accurate hyperfine coupling values obtained

Identified limitations of Gaussian basis sets in core regions

Demonstrated effectiveness of PAW method for spin density calculations

Abstract

We identify the shortcomings of existing ab initio quantum chemistry calculations for the hyperfine couplings in the recently characterized azafullerene, C59N. Standard gaussian basis sets in the context of all--electron calculations are insufficient to resolve the spin density near the cores of the atoms. Using the Projector Augmented Wave method implemented on top of a standard pseudopotential plane--wave density--functional framework, we compute significantly more accurate values for the Fermi contact interaction.