First principles determination of the model parameters in $\kappa$-(ET)$_2$Cu$_2$(CN)$_3$

TL;DR

This paper derives Hubbard model parameters for $$-(ET)$_2$Cu$_2$(CN)$_3$ using ab initio DFT, benchmarking different computational approaches to improve understanding of its electronic properties.

Contribution

It provides a comprehensive ab initio methodology for accurately determining model parameters for $$-(ET)$_2$Cu$_2$(CN)$_3$, comparing various computational methods.

Findings

Consistent parameter values across different computational approaches.

Comparison with extended Huckel calculations.

Implications for understanding the material's electronic properties.

Abstract

We present a detailed study of the derivation of the Hubbard model parameters for $\kappa$-(ET)$_2$Cu$_2$(CN)$_3$ in the framework of {\it ab initio} Density Functional Theory. We show that calculations with different (i) wavefunction basis, (ii) exchange correlation functionals and (iii) tight-binding models provide a reliable benchmark for the parameter values. We compare our results with available extended H\"uckel molecular orbital calculations and discuss its implications for the description of the properties of $\kappa$-(ET)$_2$Cu$_2$(CN)$_3$. The electronic properties of $\kappa$-(ET)$_2$Cu(SCN)$_2$ are also briefly discussed.