Likewise, group theory helps predict the changes in physical properties that occur when a material undergoes a phase transition, for example, from a cubic to a tetrahedral crystalline form. An example is ferroelectric materials, where the change from a paraelectric to a ferroelectric state occurs at the Curie temperature and is related to a change from the high-symmetry paraelectric state to the lower symmetry ferroelectic state, accompanied by a so-called soft phonon mode, a vibrational lattice mode that goes to zero frequency at the transition. COUNT 4
QSN1 What aids in predicting changes of physical traits? ANS1 group theory QSN2 What stage of a physical transformation can group theory be used to make prediction? ANS2 phase transition QSN3 What temperature causes the change of ferroelectric materials? ANS3 Curie temperature QSN4 What term describes the vibrational lattice mode that turns to 0 frequency at the change? ANS4 soft phonon mode