  We present a mean-field theory to explain the thermo-orientation effect in an
off-centre Stockmayer fluid. This effect is the underlying cause of thermally
induced polarisation and thermally induced monopoles, which have recently been
predicted theoretically. Unlike previous theories that are based either on
phenomenological equations or on scaling arguments, our approach does not
require any fitting parameters. Given an equation of state and assuming local
equilibrium, we construct an effective Hamiltonian for the computation of local
Boltzmann averages. This simple theoretical treatment predicts molecular
orientations that are in very good agreement with simulation results for the
range of dipole strengths investigated. By decomposing the overall alignment
into contributions from the temperature and density gradients, we shed further
light on how the non-equilibrium result arises from the competition between the
two gradients.
