Investigation of vibration spectrum ferroelectric semiconductor SbSBr nanowire

The temperature dependence of vibration spectra of one SbSBr chain (nanowire) in the direction of the c(z)-axis has been calculated in quasiharmonic approximation by diagonalization of dynamical matrix. The vibrational frequencies in the direction of c(z)-axis have been derived by fitting of the experimental low-frequency ωs2 of soft infrared (IR) mode of bulk-size SbSBr with the theoretical quasiharmonic low-frequency ω2 of SbSBr nanowires. In this work the nature of anharmonism and temperature dependence of force constants between atoms in SbSBr crystal along c(z)-axis have been discussed. The anharmonism of all soft (at BZ k=0) modes has been created by the interaction between phonons.