Is there a correlation between the first sharp diffraction peak and the low frequency vibrational behavior of glasses?

Neutron-diffraction and light-scattering studies have been performed on a network glass subject to structural modifications. Large changes of the first sharp diffraction peak (FSDP) and the low frequency dynamics (the boson peak) are demonstrated by gradually changing the intermediate-range structural ordering, the short-range order being preserved. A recently suggested ``universal'' correlation for glasses between the positions of the FSDP and the boson peak is shown to fail; in fact opposite trends are observed.