Lattice Dynamics of Ferroelectric SbSBr Crystal

Abstract

The temperature dependence of phonon dispersion, total and partial phonon DOS of SbSBr crystal have been determined in paraelectric phase at T = 30 K and in ferroelectric phase at T = 11 K using FP—LAPW method in the framework of DFT along with the GGA approximation. Temperature dependence of total and partial phonon DOS for Sb, S and Br atoms where used for calculation of the vibration free energy of the unit cell F_vib and contribution from Sb, S and Br atoms to the free energy F_i,μ along c(z) —axis in quasiharmonic approximation in paraelectric and ferroelectric phases in temperature range from 11 K to 294 K. For investigation of softening effect nature of phonons along c(z) —axis the mean-squared displacements of Sb, S and Br atoms in x -, y -, z - direction have been calculated in quasiharmonic approximation in ferroelectric and paraelectric phases.

PACS:

• 63.20.D-
• 65.40.-b
• 71.15.Mb
• 71.20.Nr