  For special coupling ratios, the one-dimensional (1D) s=1/2 Heisenberg model
with antiferromagnetic nearest and next-nearest neighbor interactions has a
pure dimer ground state, and the 1D s=1 Heisenberg model with antiferromagnetic
bilinear and biquadratic interactions has an exact valence-bond-solid ground
state. The recursion method is used to calculate the T=0 spin dynamic structure
factor for both models and, for the s=1/2 model, also the dimer dynamic
structure factor. New results for line shapes and dynamically relevant
dispersions are obtained.
