Thursday, June 6, 2013

1306.1074 (Martin Nuss et al.)

Ab-initio effective model for electronic properties of the quasi
one-dimensional purple bronze Li0.9Mo6O17

Martin Nuss, Markus Aichhorn
We investigate the electronic structure of the strongly anisotropic, quasi low dimensional purple bronze Li0.9Mo6O17. Building on all-electron ab-initio band structure calculations we obtain an effective model in terms of four maximally localized Wannier orbitals, which turn out to be far from atomic like. We find two half-filled orbitals arranged in chains running along one crystallographic direction, and two full orbitals in perpendicular directions, respectively. An even more minimalistic effective model with reduced dimensionality, comprised of only two chains per unit cell with inter-chain coupling, is derived. Transport properties of these models show high anisotropy, reproducing trends of the experimentally determined highly anisotropic values for the dc conductivity. We also consider basic effects of electron-electron interactions using the (extended) Variational Cluster Approach and Dynamical Mean Field Theory. We find good agreement with experimental photo emission data when using a moderate on-site interaction of the order of the bandwidth. The obtained models provide a profound basis for further investigations on low-energy Luttinger liquid properties or to study electronic correlations within computational many-body theory.
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