Studies on the electronic structure of trigonal selenium and tellurium using the effective core potential approximation

✍ Scribed by P. Saalfrank; P. Otto; J. Ladik

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 553 KB
• Volume: 153
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(88)85242-4

✦ Synopsis

The electronic properties of quasi-one-dimensional models for trigonal selenium and tellurium are studied using the ab initio Hartree-Fock scheme with non-local exchange. The core electrons are replaced by effective core potentials. We determine the energy bands of the single helices and compare our results to earlier calculations. The band gap at A is investigated with inclusion of up to six nearest-neighbour chains. Interchain interactions were computed using Hartree-Fock calculations and London's formula for dispersion energy. The interaction is stabilizing, weaker than normal chemical bonding but stronger than van-der-Waals-type interactions. Cohesive energies are in reasonable agreement with experiment. The remarkable increase of electrical conductivity with increasing pressure is explained: the direct gap at A decreases with increasing pressure for a double-chain model of selenium.