  The problem of the observable equilibrium domain structure in pure
antiferromagnets (and other thermoelastics) is investigated with the use of
continuous elasticity theory. It is shown that completely rigid surface
produces the imaginary ``incompatibility elastic charges'' analogous to the
surface magnetic charges in ferromagnets. Corresponding long-range field is
shown to contribute into the ``stray'' energy of the sample that governs an
appearance of the domain structure, the contribution from the ``elastic
charges'' being proportional to the sample volume. Competition between the
elastic ``stray'' field that favors inhomogeneous strain distribution, and
external field that tends to homogenize the sample, provides the reversible
reconstruction of the domain structure under the action of external magnetic
field.
