Kazuma Nakamura, Yoshihide Yoshimoto, Masatoshi Imada
We present ab initio two-dimensional extended Hubbard-type multiband models for EtMe_3Sb[Pd(dmit)_2]_2 and \kappa-(BEDT-TTF)_2Cu(NCS)_2, after a downfolding scheme based on the constrained random phase approximation (cRPA) and maximally-localized Wannier orbitals, together with the dimensional downfolding. In the Pd(dmit)_2 salt, the antibonding state of the highest occupied molecular orbital (HOMO) and the bonding/antibonding states of the lowest unoccupied molecular orbital (LUMO) are considered as the orbital degrees of freedom, while, in the \kappa-BEDT-TTF salt, the HOMO-antibonding/bonding states are considered. Accordingly, a three-band model for the Pd(dmit)_2 salt and a two-band model for the \kappa-(BEDT-TTF) salt are derived. We derive single band models for the HOMO-antibonding state for both of the compounds as well.
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http://arxiv.org/abs/1208.3954
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