Lattice vibrational modes in changchengite from Raman spectroscopy and first principles electronic structure

We measured room-temperature phonon Raman spectra of changchengite (IrBiS) and compared the experimental wavenumbers to theoretical ones obtained by means \emph{ab initio} density-functional-theory calculations in presence absence spin-orbit coupling effects. Combining two different excitation photon energies all symmetry predicted modes are experimentally observed. The electronic properties IrBiS found be similar recently studied isostructural compound IrBiSe showing a large Dresselhaus valence band splitting. A good agreement between theoretically is only when lattice parameter constrained value. inclusion spin orbit does not significantly affect wavenumbers.