Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 34: Methods in Computational Materials Modelling (methodological aspects, numerics)
MM 34.5: Vortrag
Donnerstag, 4. April 2019, 11:15–11:30, H44
The driving force behind the distortion of 1D monatomic chains - Peierls theorem revisited — •Daniela Kartoon1,2, Uri Argaman1, and Guy Makov1 — 1Materials Engineering Department, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel — 2NRCN-Nuclear Research Center Negev, Beer Sheva IL 84190, Israel
The onset of distortion in one-dimensional monatomic chains with partially filled valence bands is considered to be well-established by the Peierls theorem, which associates the distortion with the formation of a band gap and a subsequent gain in energy. Similar mechanism is commonly used to explain the distorted structures in half-filled p-band materials. Employing modern total energy methods on both one-dimensional chains and half-filled p-band materials, we reveal that the distortion is not universal, but conditional upon the balance between distorting and stabilizing forces. Furthermore, in all systems studied, the electrostatic interactions between the electrons and ions act as the main driving force for distortion, rather than the electron band lowering at the Fermi level as is commonly believed. The main stabilizing force which drives the materials toward their symmetric arrangement is derived from the electronic kinetic energy. Both forces are affected by the external conditions, e.g. stress, and consequently the instability of one-dimensional nanowires is conditional upon them. This suggests a more general mechanism of high-to-low symmetry transitions, and may shed new light on the distortion of more complex structures.