ORIENTATIONAL QUADRUPOLAR GLASS IN ORTHO-PARA HYDROGEN MIXTURES .1. MEAN-FIELD MICROSCOPIC THEORY

The mean-field theory of the quadrupolar glass (QG) is presented using microscopic approach. It is shown that the reaction-polarization effe cts caused by short-range spatial correlations are well distinguished from those of random-bond spin glasses. They control the QG concentrat ion threshold and result in an incomplete orientational order. The QG ground state (zero quadrupolization, unsaturated Edwards-Anderson-type orientational order parameter) is predicted Thermodynamic characteris tics, namely entropy, pressure and free energy as well as the related heat capacity and Gruneisen parameter ale estimated The ground-state f indings (incomplete order, residual entropy) are similar to those of s hort-range Potts glasses. A correspondence between density matrix and mean field treatment to the QG problem is also discussed.