Max-Planck Inst. Festkoerperforsch., Stuttgart , D-7000/80, Fed. Rep. Ger.

Full band-structure calcns. were performed for several Chevrel phases. The conduction band is eg-like throughout most of the Brillouin zone, but near the center one finds strong t1u character where t1u and eg are bonding-state symmetries. The t1u(eu) state is a Mo-X intercluster pd.pi. antibond, and its occupancy decreases as one proceeds from the 24- to the 20-electron compds. This explains the obsd. decrease of the intercluster distance; it leads to nonrigid-band behavior, and may be a source of strong electron-phonon coupling to low-frequency, external modes. Moreover, the eg-t1u mixing gives rise to crit.-field anisotropy. The 22-electron compd. BaMo6S8 and EuMo6S8 with half-filled e-bands are semimetallic or semiconducting in their low-temp. phase.
 

Supercond. d- f-Band Met., Proc. Conf., 4th (1982), 161-5. Editor(s): Buckel, W.; Weber, w. Publisher: KFK, Karlsruhe, Fed. Rep. Ger. CODEN: 50IDAE.