  Using density functional theory implemented within the generalized gradient
approximation, a new non-magnetic insulating ground state of solid oxygen is
proposed and found to be energetically favored at pressures corresponding to
the $\epsilon$-phase. The newly-predicted ground state is composed of linear
herringbone-type chains of O$_2$ molecules and has {\it Cmcm} symmetry (with an
alternative monoclinic cell). Importantly, this phase supports IR-active
zone-center phonons, and their computed frequencies are found to be in broad
agreement with recent infrared absorption experiments.
