Publication

Intermediate range order and bonding character in disordered network-forming systems

Alfredo Pasquarello
1999
Journal Articles

Abstract

The close electronegativity of Ge and Se makes disordered GeSe2 systems ideally suited to investigate the relation between intermediate range order and bonding character. First-principles molecular dynamics simulations were carried out on liquid GeSe2 using two state-of-the-art functionals, which reproduce differently the ionic character in the bonds. Only the functional favouring more ionic bonding gave rise to a first sharp diffraction peak in the calculated neutron structure factor, in excellent agreement with experiment. The appearance of a first sharp diffraction peak relates to tetrahedrally bonded Ge atoms, but an important fraction of homopolar bonds persists.

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https://infoscience.epfl.ch/entities/publication/a8622f44-ba0b-436c-996b-d504e889c607

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Alfredo Pasquarello
1999
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/a8622f44-ba0b-436c-996b-d504e889c607

About this result

Related concepts (32)

Structure factor

In condensed matter physics and crystallography, the static structure factor (or structure factor for short) is a mathematical description of how a material scatters incident radiation. The structure factor is a critical tool in the interpretation of scattering patterns (interference patterns) obtained in X-ray, electron and neutron diffraction experiments. Confusingly, there are two different mathematical expressions in use, both called 'structure factor'.

X-ray crystallography

X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information.

Chemical bond

A chemical bond is a lasting attraction between atoms or ions that enables the formation of molecules, crystals, and other structures. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds, or through the sharing of electrons as in covalent bonds. The strength of chemical bonds varies considerably; there are "strong bonds" or "primary bonds" such as covalent, ionic and metallic bonds, and "weak bonds" or "secondary bonds" such as dipole–dipole interactions, the London dispersion force, and hydrogen bonding.

Related publications (1)

Intermediate range order and bonding character in disordered network-forming systems

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