Electronic Band Structure Study of A2Mo9S11 (A=K, Rb) and K1.8Mo9S11

The electronic band structures of A2Mo9S11 (A=K, Rb) and K1.8Mo9S11 are examined by extended Hückel tight binding calculations. K2Mo9S11 and K1.8Mo9S11 are metallic and exhibit resistivity anomalies below ~115 and ~80 K, respectively. The origin of these anomalies is explained in terms of their Fermi surfaces. Our study indicates that the resistivity anomalies of these compounds are caused by the partial nesting of their two-dimensional Fermi surfaces and that both K2Mo9S11 and Rb2Mo9S11 should exhibit a charge density wave phenomenon