Pauli susceptibility at a Peierls transition

Using general arguments borrowed from magnetism, the author shows that it is short-range order parameter fluctuations close to T_c that lead to the observed behaviour of chi at a Peierls transition; in the quasi-static approximation d_chi/dT should vary as the lattice specific heat. The addition of impurities produces rounding of the d chi /dT cusp when the true phase transition is destroyed by disorder. The theory compares favourably with experiment.