COMPARISON OF THE ELECTRONIC-STRUCTURES OF LAYERED TRANSITION-METAL TRICHALCOGENIDES TASE3, TAS3, AND NBSE3

The electronic structures of the three layered transition-metal trichalcogenides NbSe3, TaS3, and TaSe3were examined by performing tight-binding band electronic structure calculations. The Fermi surfaces of these materials were also calculated to analyze their metallic and/or charge density wave properties. In these trichalcogenides MX3(M = Nb, Ta; X = S, Se) made up of prismatic MX3chains, the broken X-X bonds of their equilateral-like MX3chains and the short intra- and interlayer X•••X contacts are found to be crucial for the semimetallic properties of TaSe3and for the charge density wave phenomena of NbSe3and TaS3. For the electronic parameters of the charge density waves in NbSe3and TaS3, a quantitative agreement is obtained between the experimental observations and the present band electronic structure calculations. © 1990, American Chemical Society. All rights reserved.