1$cell vectors
21.0
3  4.9039976924631548    0.0000000000000000    0.0000000000000000
4  0.0000000000000000    4.9039976924631548    0.0000000000000000
5  0.0000000000000000    0.0000000000000000    4.9039976924631548
6 4 6
7Direct
8  0.2500000000000000    0.2500000000000000    0.2500000000000000 # Ag1
9  0.2500000000000000    0.7500000000000000    0.7500000000000000 # Ag2
10  0.7500000000000000    0.7500000000000000    0.2500000000000000 # Ag3
11  0.7500000000000000    0.2500000000000000    0.7500000000000000 # Ag4
12  0.5000000000000000    0.0000000000000000    0.0000000000000000 # O1
13  0.0000000000000000    0.5000000000000000    0.5000000000000000 # O2
14  0.5000000000000000    0.0000000000000000    0.5000000000000000 # O3
15  0.5000000000000000    0.5000000000000000    0.0000000000000000 # O4
16  0.0000000000000000    0.5000000000000000    0.0000000000000000 # O5
17  0.0000000000000000    0.0000000000000000    0.5000000000000000 # O6
18