  We have extended our experimentally constrained molecular relaxation
technique (P. Biswas {\it et al}, Phys. Rev. B {\bf 71} 54204 (2005)) to
hydrogenated amorphous silicon: a 540-atom model with 7.4 % hydrogen and a
611-atom model with 22 % hydrogen were constructed. Starting from a random
configuration, using physically relevant constraints, {\it ab initio}
interactions and the experimental static structure factor, we construct
realistic models of hydrogenated amorphous silicon. Our models confirm the
presence of a high frequency localized band in the vibrational density of
states due to Si-H vibration that has been observed in a recent vibrational
transient grating measurements on plasma enhanced chemical vapor deposited
films of hydrogenated amorphous silicon.
