A new generalized Kohn-Sham method for fundamental band-gaps in solids

Area of Science:

• Solid-state physics
• Computational materials science
• Quantum chemistry

Background:

• Accurate calculation of ground-state properties and band-gaps in solids is crucial for understanding material behavior.
• Traditional methods like the local density approximation (LDA) often struggle with accurately predicting band-gaps.

Purpose of the Study:

• To develop and validate a novel computational method for calculating the ground-state properties and fundamental band-gaps of solids.
• To improve the accuracy of band-gap predictions compared to existing methods.

Main Methods:

• A generalized Kohn-Sham approach was employed, combining a local density approximation (LDA) functional with a long-range explicit exchange orbital functional.
• A specific range parameter (gamma) was derived based on the optical dielectric constant (ε∞) of solids: γ=A/(ε∞-ε), with A=0.216 a0⁻¹ and ε=0.84.

Main Results:

• The developed method accurately predicts fundamental band-gaps for a variety of solids, showing close agreement with experimental values.
• For most solids, the required range parameter (γ) was small, leading to lattice constants and bulk moduli comparable to conventional LDA calculations.
• Preliminary calculations for silicon demonstrated a general band structure consistent with experimental findings.

Conclusions:

• The hybrid LDA and explicit exchange functional approach offers a reliable method for calculating solid-state properties, particularly fundamental band-gaps.
• The derived formula for the range parameter enables accurate band-gap predictions across diverse solid materials.
• This method provides a promising tool for materials discovery and characterization.