Ml. Doublet et al., A NEW THEORETICAL APPROACH FOR THE ELECTRICAL-PROPERTIES OF TIX2 (X =S, SE, TE) PHASES WITH DENSITY-FUNCTIONAL CALCULATIONS, The Journal of chemical physics, 108(2), 1998, pp. 649-658
The electronic structures of layered transition metal dichalcogenides
TiX2 (X=S, Se, Te) have been studied with the Amsterdam Density Functi
onal package for periodic systems (ADF-BAND). The accuracy of this alg
orithm to calculate the charge transfer between the chalcogens and the
metal has been tested at different levels of approximation (local-den
sity approximation, generalized gradient corrections of Becke-Perdew a
nd Perdew-Wang, and quasirelativistic calculations). The total and par
tial density of states of the three compounds, as well as the crystal
orbital overlap population analysis, have been used to rationalize the
electronic structure of the systems. The present results show a signi
ficant pld-block band overlap for TiTe2, leading to a Te(Sp)-->Ti(3d)
electron transfer and a metallic behavior. Conversely, owing to the re
dox competition between the metal and the chalcogens, TiS2 and TiSe2 a
re predicted to be a semiconductor and a semimetal respectively. These
physical properties are discussed in terms of electron density displa
cement from the chalcogen to the titanium when going from TiS2 to TiTe
2. The relativistic effects appear to have no significant influence on
the global physical properties of these layered compounds, although t
hey slightly reduce the Te(Sp)-->Ti(3d) electron transfer. (C) 1998 Am
erican Institute of Physics.