  We present a molecular dynamics study of the collective dynamics of a
flexible model for the fragile glass-former orthoterphenyl [ S. Mossa, R. Di
leonardo, G. Ruocco, and M. Sampoli, Phys. Rev. E 62, 612 (2000)]. We study the
behavior of the coherent scattering functions, considering the density
fluctuations of both molecular and phenyl rings centers of mass; moreover we
directly simulate the neutron scattering spectra taking into account both the
contributions due to the carbon and hydrogens atoms. We compare our results
with the main predictions of the Mode Coupling Theory and with the available
coherent neutron scattering experimental data.
