Fig. 3: Evolution of phonon characteristics under tensile strain.
From: Strain-driven lone pair electron expression for thermal transport in BiCuSeO
A Phonon dispersion spectra of BiCuSeO at strains from 0% to 4%, showing frequency shifts across the Brillouin zone. B Enlarged view of the low-frequency acoustic branches (TA, TA′, and LA) under varying strain levels, indicating softening of phonon modes. C Phonon spectrum with color-coded inverse participation ratio (IPR) values, revealing the degree of phonon localization. D Representative vibrational modes at the Γ point for different frequencies, showing the atomic displacement patterns and evolution from low to high vibrational frequencies. E Relative regular residuals as a function of atomic displacements, fitted by a fourth-order polynomial. The increasing coefficients indicate enhanced anharmonicity with strain. F Grüneisen parameters (γ) across the first Brillouin zone under different tensile strains, reflecting changes in phonon anharmonicity and thermal transport properties.
