Dynamic structure factor of a spin chain with three-spin interactions in a transverse magnetic field

We investigate the spin dynamics of a quantum spin chain with three-spin interactions in a transverse magnetic field. The longitudinal dynamic structure factor is calculated in function of temperature and applied transverse magnetic fields. Calculations are performed with chains up to 14 spins with periodic boundary conditions. Both direct diagonalization and the method of recurrent relations are used. Although the calculations are done with finite chains the results can be extrapolated to the thermodynamic limit. The frequency dependence of the longitudinal dynamic structure factor at several values of temperature, magnetic field, and wave vector, is calculated and its behavior analyzed.