Ab Initio Electronic Structure Calculation for Single-Component Molecular Conductor Au(tmdt)_2 (tmdt=Trimethylenetetrathiafulvalenedithiolate)(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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We have investigated the electronic structure of Au(tmdt)_2 (tmdt=trimethylenetetrathiafulvalene-dithiolate), which is a single-component conductor showing a magnetic phase transition around 100K, by ab initio plane-wave pseudopotential calculations. A single band crosses the Fermi level. This band and the next band below are a result of the strong hybridization between the two neighboring molecular levels near the Fermi level (SOMO and HOMO-1) and the system is more properly described as quarter-filled rather than half-filled in the strong correlation regime. The Fermi surface has corrugated-sheet-like parts nearly parallel to each other. Intraband generalized susceptibility suggests the presence of a nesting vector a^*/2 (a^* is one of the reciprocal lattice vectors). Spin-polarized calculation on the doubled unit cell along the a axis (a is a lattice vector) results in an antiferromagnetic order. The nesting is not perfect and Fermi-surface pockets remain in the magnetic phase. The implications of the present calculations with regard to experimental results are discussed.
社団法人日本物理学会の論文
2005-03-15