  We present a generalization of the Luttinger-Tisza-Lyons-Kaplan (LTLK) theory
of classical ground states of Bravais lattices with Heisenberg coupling to
non-Bravais lattices. It consists of adding certain Lagrange parameters to the
diagonal of the Fourier transformed coupling matrix analogous to the theory of
the general ground state problem already published. This approach is
illustrated by an application to a modified honeycomb lattice, which has
exclusive three-dimensional ground states as well as a classical spin-liquid
ground state for different values of the two coupling constants. Another
example, the modified square lattice, shows that we can also obtain so-called
incommensurable ground states by our method.
