Keywords :
Theoretical or Mathematical/ ab initio calculations; band structure; electrical conductivity transitions; high-pressure effects; liquid semiconductors; liquid structure; metal-insulator transition; Monte Carlo methods; selenium; tight-binding calculations/ structural properties; electronic properties; high-temperature fluid Se; semiempirical tight-binding energy model; dispersion forces; ab initio calculation; liquid structures; Monte Carlo simulations; coordination number; metal-nonmetal transitions; semiconductor-metal transitions; high pressure; Se/ A7125L Electronic structure of liquid metals and semiconductors and their alloys A6120J Computer simulation of static and dynamic liquid behaviour A7115A Ab initio calculations (condensed matter electronic structure) A7115F Atomic- and molecular-orbital methods (condensed matter electronic structure) A7115Q Molecular dynamics calculations and other numerical simulations (condensed matter electronic structure) A6250 High-pressure and shock-wave effects in solids and liquids A7130 Metal-insulator transitions and other electronic transitions/ Se/el
Abstract :
[en] A semi-empirical tight-binding energy model is developed for selenium. It includes s and p electrons as well as an empirical description of the dispersion forces. The band structure parameters are obtained by fitting ab initio calculations. The simulated liquid structures are in very good agreement with the most recent X-ray scattering and EXAFS measurements. The Monte Carlo simulations performed show that the complex liquid structures observed result from the breaking and branching of the selenium chains. The total coordination number is shown to result from the balance between one-, two- and three-fold coordinated atoms. The role of these defects is discussed in relationship with the electrical conductivity of the liquid, i.e. the semiconductor-metal and metal-non-metal transitions observed at high pressure and temperature
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