  Using the pruned-enriched Rosenbluth Monte Carlo algorithm, the scattering
functions of semiflexible macromolecules in dilute solution under good solvent
conditions are estimated both in $d=2$ and $d=3$ dimensions, considering also
the effect of stretching forces. Using self-avoiding walks of up to $N = 25600$
steps on the square and simple cubic lattices, variable chain stiffness is
modeled by introducing an energy penalty $\epsilon_b$ for chain bending;
varying $q_b=\exp (- \epsilon_b/k_BT)$ from $q_b=1$ (completely flexible
chains) to $q_b = 0.005$, the persistence length can be varied over two orders
of magnitude. For unstretched semiflexible chains we test the applicability of
the Kratky-Porod worm-like chain model to describe the scattering function, and
discuss methods for extracting persistence length estimates from scattering.
While in $d=2$ the direct crossover from rod-like chains to self-avoiding walks
invalidates the Kratky-Porod description, it holds in $d=3$ for stiff chains if
the number of Kuhn segments $n_K$ does not exceed a limiting value $n^*_K$
(which depends on the persistence length). For stretched chains, the Pincus
blob size enters as a further characteristic length scale. The anisotropy of
the scattering is well described by the modified Debye function, if the actual
observed chain extension $<X>$ (end-to-end distance in the direction of the
force) as well as the corresponding longitudinal and transverse linear
dimensions $<X^2> - <X>^2$, $<R_{g,\bot}^2>$ are used.
