Table 1. Dielectric tensors shape for different crystal symmetries.

Crystal System	Point Groups	Dielectric Tensor	No. of independent elements
Cubic	23, m$\overline{3}$, 432$\overline{4}$3m, m$\overline{3}$m	$\left(\begin{array}{ccc}{\mathit{\epsilon }}_{11}& 0& 0\\ 0& {\mathit{\epsilon }}_{11}& 0\\ 0& 0& {\mathit{\epsilon }}_{11}\end{array}\right)$	1
Hexagonal, Trigonal and Tetragonal	3, $\overline{3}$, 32, 3m, $\overline{3}$m4, $\overline{4}$, 4/m, 4224mm, $\overline{4}$2m, 4/mmm6 $\overline{6}$, 6/m, 6226mm, $\overline{6}$m2, 6/mmm	$\left(\begin{array}{ccc}{\mathit{\epsilon }}_{11}& 0& 0\\ 0& {\mathit{\epsilon }}_{11}& 0\\ 0& 0& {\mathit{\epsilon }}_{33}\end{array}\right)$	2
Orthorhombic	222, mm2mmm	$\left(\begin{array}{ccc}{\mathit{\epsilon }}_{11}& 0& 0\\ 0& {\mathit{\epsilon }}_{22}& 0\\ 0& 0& {\mathit{\epsilon }}_{33}\end{array}\right)$	3
Monoclinic	2, m, 2/m	$\left(\begin{array}{ccc}{\mathit{\epsilon }}_{11}& 0& {\mathit{\epsilon }}_{13}\\ 0& {\mathit{\epsilon }}_{22}& 0\\ {\mathit{\epsilon }}_{13}& 0& {\mathit{\epsilon }}_{33}\end{array}\right)$	4
Triclinic	1, $\overline{1}$	$\left(\begin{array}{ccc}{\mathit{\epsilon }}_{11}& {\mathit{\epsilon }}_{12}& {\mathit{\epsilon }}_{13}\\ {\mathit{\epsilon }}_{12}& {\mathit{\epsilon }}_{22}& {\mathit{\epsilon }}_{23}\\ {\mathit{\epsilon }}_{13}& {\mathit{\epsilon }}_{23}& {\mathit{\epsilon }}_{33}\end{array}\right)$	6