  Quantum field theory predicts Weyl semimetals to possess a peculiar response
of the longitudinal current density to the application of a DC magnetic field.
Such a response function has been shown to be at odds with a general result
showing the vanishing of the bulk current in an equilibrium system on any real
material with a lattice in an external magnetic field. Here we resolve this
apparent contradiction by introducing a model where a current flows in response
to a magnetic field even without Weyl nodes. We point out that the previous
derivation of a vanishing CME in the limit of vanishing real frequency is a
consequence of the assumption of periodic boundary conditions of the system. A
more realistic system with open boundary conditions is not subject to these
constraints and can have a non-vanishing CME. Consistent with recent work, we
found the finite frequency CME to be non-vanishing in general when there was a
non-vanishing Berry curvature on the Fermi surface. This does not necessitate
having a topological Berry flux as in the case of a Weyl node. Finally, we
study how the perturbation theory in magnetic field might be more stable in the
presence of disorder. Using the standard diagrammatic treatment of disorder
within the Born approximation, we have found that in a realistic disordered
system, the chiral magnetic response is really a dynamical phenomena and
vanishes in the DC limit.
