  In this paper, we provide a procedure to calculate the bremsstrahlung
spectrum for virtually any relativistic bare ion with charge 6$e$ or beyond,
$Z\ge 6$, in ultraperipheral collisions with target nuclei. We apply the
Weizs\"{a}cker-Williams method of virtual quanta to model the effect of the
distribution of nuclear constituents on the interaction of the ion with the
radiation target. This leads to a bremsstrahlung spectrum peaking at $2\gamma$
times the energy of the giant dipole resonance ($\gamma$ is the projectile
energy in units of its rest energy). A central ingredient in the calculation is
the cross section for elastic scattering of photons on the ion. This is only
available in the literature for a few selected nuclei and, usually, only in a
rather restricted parameter range. Hence we develop a procedure applicable for
all $Z\geq6$ to estimate the elastic scattering. The elastic cross section is
obtained at low to moderate photon energies, somewhat beyond the giant dipole
resonance, by means of the optical theorem, a dispersion relation, and data on
the total absorption cross section. The cross section is continued at higher
energies by invoking depletion due to loss of coherence in the scattering. Our
procedure is intended for any ion where absorption data is available and for
moderate to high energies, $\gamma \gtrsim 10$.
