First principles determination of the model parameters in κ‐(ET)2Cu2(CN)3κ‐(ET)2Cu2(CN)3

We present a detailed study of the derivation of the Hubbard model parameters for κ‐(ET)2Cu2(CN)3κ‐(ET)2Cu2(CN)3 in the framework of 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 Hückel molecular orbital calculations and discuss its implications for the description of the properties of κ‐(ET)2Cu2(CN)3κ‐(ET)2Cu2(CN)3. The electronic properties of κ‐(ET)2Cu(SCN)2κ‐(ET)2Cu(SCN)2 are also briefly discussed.