Table 14.

Reduction from 6 to 2

Space group of unstrained crystal, order 6 per lattice point		If stressed so that z ∥ X, Y, or Z			Space group of strained crystal, order 2 per lattice point
		Coordinates referred to axes of unstrained crystal
No.	Symbol	1st Subset	2d Subset	3d Subset	No.	Symbol
168	P6	(x,y, z) ($\overline{x}$$\overline{y}$, z)	($\overline{y}$,x-y, z) (y,y-x, z)	(y-x,$\overline{x}$, z) (x-y,x, z)	3	P2
169	P61	(x,y, z) ($\overline{x}$$\overline{y}$, ½+ z)	($\overline{y}$,x-y, ⅓+ z) (y,y-x,⅚+ z)	(y-x,$\overline{x}$, ⅔+z) (x-y,x,⅙+ z)	4	P21
170	P65	(x,y, z) ($\overline{x}$$\overline{y}$, ½+ z)	($\overline{y}$,x-y,⅔+z) (y,y-x,⅙+ z)	(y-x,$\overline{x}$, ⅓+ z) (x-y,x,⅚+ z)	4	P21
171	P62	(x,y, z) ($\overline{x}$$\overline{y}$, z)	($\overline{y}$,x-y, ⅔+z) (y,y-x, ⅔+z)	(y-x,$\overline{x}$, ⅓+ z) (x-y,x, ⅓+ z)	3	P2
172	P64	(x,y, z) ($\overline{x}$$\overline{y}$, z)	($\overline{y}$,x-y, ⅓+ z) (y,y-x, ⅓+ z)	(y-x,$\overline{x}$, ⅔+z) (x-y,x, ⅔+z)	3	P2
173	P63	(x,y, z) ($\overline{x}$$\overline{y}$, ½+ z)	($\overline{y}$,x-y, z) (y,y-x, ½+ z)	(y-x,$\overline{x}$, z) (x-y,x, ½+ z)	4	P21