Rigid Unit Modes in disordered nepheline: a study of a displacive incommensurate phase transition - Hayward, S. A.; Pryde, A. K. A.; de Dombal, R.F.; Carpenter, M. A.; Dove, M. T. (Springer, 2000)
http://dx.doi.org/10.1007/s002690050257
Keywords: V; TE-TZ; U