A DYNAMIC CORRELATION-FUNCTION FROM INELASTIC NEUTRON-SCATTERING DATA

For a non-dispersive vibrational mode in a solid the Q-dependence of t he scattering function S(Q, E) at the energy of the mode contains info rmation relating to the atomic displacements of the mode. An empirical approach to the analysis of such data has recently been employed wher eby a Fourier transform is used to obtain a 'dynamic correlation funct ion' in real-space. This technique is demonstrated using new data on a morphous boron. The theoretical basis of the method is discussed and i t is shown that, whilst the result of the Fourier transform is not a t rue correlation function, the method is capable of providing informati on concerning the atomic distances which participate in a particular v ibration and the relative phase involved.