https://doi.org/10.1140/epjb/s10051-026-01137-y
Research - Condensed Matter
Electronic, optical, vibrational, and thermodynamic insights into KLi2Bi: unveiling its topological semimetal behaviour
Department of Applied Science and Humanity, Parul Institute of Applied Sciences, Parul University, Vadodara, Gujarat, India
a
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Received:
11
December
2025
Accepted:
3
February
2026
Published online:
25
February
2026
Abstract
The present research explores the first-principles investigation of the electronic, optical, vibrational, and thermodynamic properties of the topological intermetallic compound KLi2Bi. The electronic band structure shows the Fermi level located at 0 eV with valence and conduction bands overlapping in its vicinity, confirming a semimetallic or narrow-gap semiconducting character. Strong interband transitions near the Fermi level dominate the optical response, yielding a high static refractive index of~4.5, which rapidly decreases to~1.5 within the first 5 eV due to intense electronic dispersion. The extinction coefficient reaches a maximum of~2.5 at~2 eV, corresponding to strong optical absorption, while the dielectric function exhibits a pronounced peak with Re(ε) ≈ 16 and Im(ε) ≈ 14 at~2 eV, reflecting strong spin–orbit–driven interband transitions associated with Bi-p states. The absorption coefficient exceeds 2.2 × 106 cm⁻1 at low energies, with a prominent peak of~1.4 × 106 cm⁻1 near 10 eV, indicating efficient photon harvesting over a wide spectral range. The energy-loss function shows a dominant plasmon peak of~2.5 at~2 eV, while the reflectivity reaches~0.55 near 2 eV and drops below 0.1 above 10 eV, signifying ultraviolet transparency. Phonon dispersion curves exhibit no imaginary frequencies, confirming dynamic stability, and Raman spectra reveal a strong mode at~250 cm⁻1, evidencing significant electron–phonon coupling. Thermodynamically, the Debye temperature increases from~100 K to~700 K up to 1000 K, while the free energy becomes~− 4 eV at 1000 K, demonstrating high-temperature stability. These results establish KLi2Bi as a dynamically stable topological semimetal with strong optical activity and plasmonic response, making it a compelling candidate for optoelectronic, plasmonic, and topological-photonic applications.
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© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
