The relation between phonon frequencies and interatomic force constants

A method involving Fourier series is given by which interatomic force constants can be systematically derived from measured phonon frequencies and eigenvectors. The resolution in wave-vector at which the measurements must be made is related to the range of the force constants. In agreement with recent work by Leigh, Szigeti & Tewary, it is concluded that when the eigenvectors are not known there is no unique solution for the force constants. This is illustrated by a simple numerical example.