  A 2-site 2-electron model with s- and p-states on each site, having
constrained average site-spins S_a, S_b, with angle theta between them, simpler
than the previous closely-related model of Katsura et al (KNB), is considered.
Intra-site Coulomb repulsion and inter-site spin-orbit coupling V_(SO) are
included. The ground state has an electric dipole moment pi consistent with the
result of KNB, pi proportional to R x (S_a x S_b) = f, R connecting the two
sites, and application to a spiral leads to ferroelectric polarization with
direction f, also in agreement with the previous result. However, the present
result shows the expected behavior pi goes to 0 as V_(SO) goes to 0, unlike the
previous one.
