A detailed analysis of the LaBGeO₃ single crystal vibration spectra has been carried out. The lattice vibration calculation based on a short-range model potential function provides the theoretical background of this study, The model function parameters are taken from ab initio quantum mechanic calculations of molecular clusters containing structural fragments. When applied to the lattice dynamics calculations the model satisfactorily reproduces the spectra of IR- and Raman-active modes. The main goal of this lattice dynamics study was to find the proper atomic rearrangement associated with a ferroelectric phase transition.