Analysis of the optic-type collective mode in liquid selenium to determine the local structure

We have performed inelastic neutron scattering measurements for liquid selenium to investigate the dynamic structure, S (Q,E), of the chainlike molecules in the liquid state. We observed a distinct optic-type mode at around 31 meV, whose Q dependence of the intensity, S (Q,E∼31 meV), was found to be reproduced by a simple approximation of "three-body" model. We propose the possibility of extracting structural parameters such as bond length and angle by constant E spectra by the use of this simple model, which at the same time provides us a clearcut physical meaning of the Q dependences.