Bandgapfrom

Bandgapfrom is a generic term used in materials science to describe methods and software routines for determining a material's band gap energy from data sources such as optical spectra or electronic-structure calculations. It covers both experimental and computational approaches.

In experimental contexts, bandgapfrom often relies on the optical absorption edge measured by UV-Vis spectroscopy. The onset of absorption is converted to energy, and a Tauc plot may be used to distinguish direct and indirect transitions. For direct-bandgap materials, the linear region of (alpha h nu)^2 versus h nu yields the optical gap; for indirect materials, (alpha hnu)^{1/2} versus h nu is used. Photoluminescence peak energies can also serve as optical-gap estimates in high-quality samples.

In computational workflows, bandgapfrom refers to extracting the gap from calculated band structures. The fundamental (electronic) gap from density functional theory is often underestimated and can be improved with many-body methods such as GW or by applying a scissor correction. The output may be the fundamental gap, the optical gap, or both, depending on the method.

In software, bandgapfrom is typically a function or module that takes spectral data, structural information, or computed band structures and returns a band-gap value in electron volts, with metadata about method and uncertainty.

Limitations include material dependence, excitonic effects, temperature, and data quality. Bandgapfrom results should be interpreted in the context of the chosen approach.