  We present a comparative theoretical and experimental study of dynamic
structure factors (momentum-dependent loss functions) of the noble metals Cu,
Ag, and Au in the energy range of 0$-$60 eV. The emphasis is on theoretical
results that are compared with new as well as available experimental data.
Dynamic structure factors are calculated within the linear-response formalism
of time-dependent density-functional theory, using the full-potential
linearized augmented plane-wave (FP-LAPW) method. For the studied energy range,
local-field effects are found to be very important for Ag and Au and only
marginally relevant for Cu. We present an explanation for this surprising
behavior. Loss functions of all three metals possess a complex multi-peak
structure. We classify the features in the loss function as being related to
collective excitations, interband transitions, or mixed modes. The impact of
short-range correlations on the dynamic response functions are evaluated by
comparing the results of the random-phase approximation to those of the
time-dependent local-density approximation. Exchange correlation effects are
found to be weak for small momentum transfers, but increasingly important for
larger momenta. The calculated structure factors agree well with experiments.
