21. The matrix corresponding to a 3-fold rotation along z-axis using crystallographic system is:
(a)
À1 1 0
À1 0 0
0 0 À1
0
@
1
A
(b)
1 À1 0
1 0 0
0 0 1
0
@
1
A
(c)
0 1 0
À1 1 0
0 0 À1
0
@
1
A
(d)
0 À1 0
1 À1 0
0 0 1
0
@
1
A
22. The matrix corresponding to a 6-fold rotation along z-axis using crystallographic system is:
(a)
À1 1 0
À1 0 0
0 0 À1
0
@
1
A
(b)
1 À1 0
1 0 0
0 0 1
0
@
1
A
(c)
0 1 0
À1 1 0
0 0 À1
0
@
1
A
(d)
0 À1 0
1 À1 0
0 0 1
0
@
1
A
23. The matrix corresponding to a 6-fold rotation along z-axis using crystallographic system is:
(a)
À1 1 0
À1 0 0
0 0 À1
0
@
1
A
(b)
1 À1 0
1 0 0
0 0 1
0
@
1
A
(c)
0 1 0
À1 1 0
0 0 À1
0
@
1
A
(d)
0 À1 0
1 À1 0
0 0 1
0
@
1
A
256
6 Unit Cell Symmeteries and Their Representations