  We present self-consistent numerical calculations of the electronic structure
of parallel Coulomb-confined quantum wires, based on the Hohenberg-Kohn-Sham
density functional theory of inhomogeneous electron systems. We find that the
corresponding transverse energy levels of two parallel wires lock together when
the wires' widths are similar and their separation is not too small. This
energy level locking is an effect of Coulomb interactions and of the the
density of states singularities that are characteristic of quasi-
one-dimensional Fermionic systems. In dissimilar parallel wires level lockings
are much less likely to occur. Energy level locking in similar wires persists
to quite large wire separations, but is gradually suppressed by inter-wire
tunneling when the separation becomes small. Experimental implications of these
theoretical results are discussed.
