  Interactions with electronic excitations can soften and/or broaden phonons.
They are greatly amplified at wavevectors Q+- that connect parallel (nested)
sheets of the Fermi surface. In such a case, called a Kohn anomaly, the phonon
dispersion sharply dips and its linewidth has a maximum at Q+-. Here we present
results of inelastic x-ray scattering measurements that uncovered soft phonons
in chromium far from Q+-. They appear in addition to the previously reported
soft phonons at Q+-. Calculations in the local density approximation (LDA) show
that the new anomalies originate from enhanced electron-phonon coupling. A
similar mechanism may explain phonon anomalies away from nesting wavevectors in
copper oxide superconductors and other compounds.
