Ab-initio calculation of surface phonons at the Sb2Te3(111) surface

Davide Campi
2018
Journal paper

Density functional perturbation theory is used to study the phonon dispersion relations at the (111) surface of the topological insulator Sb2Te3. Inelastic Helium atom scattering experiments at the (111) surface of the similar Bi2Se3 topological insulator suggested the occurrence of a deep Kohn anomaly related to the presence of the topological surface metallic state. A slab made of three Sb2Te3 quintuple layers is used here to model the (111) surface. This geometry is shown to be sufficient to generate metallic Dirac surface states in good agreement with experimental data from Angle Resolved Photoemission Spectroscopy. The inclusion of spin-orbit interaction in the calculations of surface phonons at wavevectors corresponding to Fermi surface nesting inside the Dirac cone allow us to address the possible occurrence of a Kohn anomaly in Sb2Te3(111) as well. No evidence is found in our calculations for any Kohn anomaly in Sb2Te3 due to electronic transitions across the Dirac cone. (C) 2018 Elsevier B.V. All rights reserved.

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Davide Campi
2018
Journal paper

Abstract

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https://infoscience.epfl.ch/record/263348?ln=en

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Related concepts (3)

Density functional theory

Density-functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-body systems, in particular atoms, molecules, and the condensed phases. Using this theory, the properties of a many-electron system can be determined by using functionals, i.e. functions of another function. In the case of DFT, these are functionals of the spatially dependent electron density.

Ab initio quantum chemistry methods

Ab initio quantum chemistry methods are computational chemistry methods based on quantum chemistry. The term ab initio was first used in quantum chemistry by Robert Parr and coworkers, including David Craig in a semiempirical study on the excited states of benzene. The background is described by Parr. Ab initio means "from first principles" or "from the beginning", implying that the only inputs into an ab initio calculation are physical constants.

Experimental data

Experimental data in science and engineering is data produced by a measurement, test method, experimental design or quasi-experimental design. In clinical research any data produced are the result of a clinical trial. Experimental data may be qualitative or quantitative, each being appropriate for different investigations. Generally speaking, qualitative data are considered more descriptive and can be subjective in comparison to having a continuous measurement scale that produces numbers.