Physical interpretation of spectral broadening in finite-cell Kubo–Greenwood calculations

Determine the physical connection between thermal lattice fluctuations and the spectral broadening used in finite-cell Kubo–Greenwood calculations of electron transport in amorphous materials.

Background

Finite-cell Kubo–Greenwood calculations require spectral broadening to replace the discrete energy-conservation delta functions of a finite supercell. Molecular-dynamics-based Kubo–Greenwood simulations separately incorporate thermal lattice fluctuations by averaging conductivity over thermally sampled atomic configurations.

The review identifies an unresolved issue in interpreting how these two effects are physically related. Clarifying this connection is important for distinguishing numerical smoothing from genuine temperature-dependent spectral broadening and for improving the predictive reliability of transport calculations in amorphous materials.

References

Although recent MD-KG [19,20] and MD-NEGF [46,47] simulations provide practical routes for incorporating thermal lattice fluctuations through molecular-dynamics sampling, the physical connection between such fluctuations and the spectral broadening used in finite-cell KG calculations remains unclear.

— Electron transport in amorphous materials: from localization to predictive transport modeling  (2608.17814 - Lee, 18 Aug 2026) in Section 5, Summary and outlook