M. Leuchs et W. Kiefer, CONSTRUCTION OF 3RD AND 4TH RANK TENSORS FOR THE TRICLINIC, MONOCLINIC AND ORTHORHOMBIC CRYSTAL CLASSES, Journal of Raman spectroscopy, 25(5), 1994, pp. 317-320
A simple method is described for constructing symmetry-allowed polar t
ensors for n-photon processes of rank three and four by using polar te
nsors of rank one and two. The consideration is restricted here to the
triclinic, monoclinic and orthorhombic crystal classes and intrinsic
symmetry is not taken into account. Expansion to higher order tensors
is possible.