Perturbing finite temperature multicomponent DFT 1D Kohn-Sham systems: Peierls gap & Kohn anomaly

Area of Science:

• Condensed Matter Physics
• Quantum Materials Science
• Computational Materials Science

Background:

• Predicting properties of quantum materials (e.g., critical temperature, gap parameter) is a major challenge for developing new quantum technologies.
• Quantum sensing, electronics, and computation rely on these materials, but first-principles calculations are hindered by the many-body problem.
• Full electron-nuclear quantum calculations are computationally infeasible for the foreseeable future.

Purpose of the Study:

• To demonstrate that the Peierls effect and Kohn anomaly are inherent features of Kohn-Sham (KS) equations.
• To develop a practical, predictive strategy for electro-phonon related material properties, including temperature dependence.
• To extend this approach to 2D and 3D materials.

Main Methods:

• Utilized finite temperature, multi-component density functional theory (DFT) as a practical alternative to ab initio calculations.
• Employed a perturbative scheme applied to the Kohn-Sham equations.
• Calculated temperature-dependent ionic density for a 1D lattice and analyzed its effect on the electronic band structure via Fourier transformation.

Main Results:

• The Peierls effect and Kohn anomaly were shown to be natural outcomes of the KS equations without requiring additional parameters.
• Derived the temperature-dependent ionic density and its influence on the electronic band structure.
• Successfully derived the Kohn anomaly by perturbing the KS ionic equation with conduction electron density, linked to Peierls effect phonon distortion.

Conclusions:

• Finite temperature DFT combined with perturbation theory provides a workable strategy for predicting quantum material properties.
• The Peierls effect and Kohn anomaly are fundamental to the KS framework, simplifying predictions of electro-phonon coupling.
• This method offers a pathway to understanding and designing advanced quantum materials with temperature-dependent behaviors.