  For any classical statistical-mechanics model with a discrete state space,
and endowed with a dynamics satisfying detailed balance, it is possible to
generalize the Rokhsar-Kivelson point for the quantum dimer model. That is, a
quantum Hamiltonian can be constructed (on the same state space), such that the
ground state wavefunction coincides with the classical equilibrium
distribution. Furthermore the excited eigenstates correspond to classical
relaxation modes, which (in cases with a symmetry or conserved quantity)
permits extraction of the dispersion law of long-wavelength excitations. The
mapping is natural mainly when the states have equal weight, as is typical of a
highly frustrated model. Quantum and classical correlation functions are
related by analytic continuation to the imaginary time axis.
