On the possibility of observing macroscopic properties in a finite crystal that are forbidden by the symmetry point group
Levanyuk A.P., Gladki V.V.
The difference between the symmetry group of a finite crystal and its point group is examined. These differences account for the point-group-forbidden components of the quadrupole moment, which are especially large in crystals with an incommensurable superlattice. The possibility of observing other macroscopic properties, which are forbidden by the point group, is discussed.