  The IR- and Raman-active phonon frequencies, as well as the elastic constants of orthorhombic GeSe, were calculatedas a function of hydrostatic pressure using the method of density functional in the ABINIT software package. Comparison with the published results of theoretical calculations and experimental data of the pressure dependence of Raman-active phonons has been carried out. Our calculations show that at a pressure of about 29 GPa the crystal structure of GeSe undergoes a continuous transition from simple orthorhombic to base-centered orthorhombic lattice. 
The pressure dependence of the phonon spectra and elastic modulus of   orthorhombic : the method of local density functional