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MM: Fachverband Metall- und Materialphysik

MM 45: Computational Materials Modelling - Low dimensional systems

MM 45.1: Vortrag

Mittwoch, 18. März 2020, 17:15–17:30, IFW B

Density functional theory of structural distortion in one dimensional and three dimensional structures — Uri Argaman, Daniela Kartoon, and •Guy Makov — Dept. of Materials, Ben-Gurion University, Beer-Sheva, 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. Many half-filled p-band materials form complex, semiconducting or semi-metallic crystallographic structures, which are commonly conceived of as distortions of simpler, higher-symmetry structures. Employing modern total energy methods on the test cases of elemental chains and lattices, 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 structures towards their symmetric arrangement is the electronic kinetic energy. Both forces are affected by the external conditions, e.g., stress, and consequently the instability is conditional upon them. These results may shed light on the distortion of more complex structures. Funding Acknowledgement: Support of the Israel Ministry of Science and Technology is acknowledged.