SUMMARY
We study the lattice dynamics of the zincblende phase of bulk group-III nitrides using the linear chains models. It is shown that the 3D oscillation problem reduces to uncoupled linear chain equations for high symmetry directions. The relation between the 3D and 1D force constants has been investigated. Our study helps to understand better the richness of the linear chain models. We also show how to fit the 3D bulk force constants (and consequently the whole dynamical matrix) from a few points, either experimental or theoretical. Results for GaN and AlN are reported.