-    CRISTOBALITE     -    SiO2

The crystal structure is fully relaxed (both unit cell parameters and atomic positions under symmetry constraints) at 40GPa 

Crystal Structure 


Because of the translational symmetry all the calculations are performed in the primitive unit cell and not in the conventional unit cell. The following information regarding the structure is given with respect to this primitive unit cell, which sometimes can take an unintuitive shape.

Symmetry (experimental): 

Space group:  Theo P-1 
Lattice parameters (Å):  6.7500  4.0633  6.8344 
Angles (°):  90  90  90 

Symmetry (theoretical): 

Space group:  Theo P-1 
Lattice parameters (Å):  6.4418  3.8764  6.6721 
Angles (°):  90.13  98.11  90.09 

Cell contents: 

Number of atoms:  24 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

Si:  0.5000  -0.0000  0.5000 
Si:  0.0000  0.5000  0.0000 
Si:  0.3584  0.9984  0.1180 
Si:  0.1349  0.4995  0.3754 
Si:  0.6416  0.0016  0.8820 
Si:  0.8651  0.5005  0.6246 
Si:  0.2731  0.4952  0.7562 
Si:  0.7269  0.5048  0.2438 
O:  0.3302  0.2266  0.3312 
O:  0.1640  0.7402  0.1667 
O:  0.6698  0.7734  0.6688 
O:  0.8360  0.2598  0.8333 
O:  0.4681  0.2345  0.7108 
O:  0.0464  0.7209  0.7949 
O:  0.5319  0.7655  0.2892 
O:  0.9536  0.2791  0.2051 
O:  0.3000  0.7317  0.5441 
O:  0.2086  0.2554  0.9568 
O:  0.7000  0.2683  0.4559 
O:  0.7914  0.7446  0.0432 
O:  0.4229  0.7615  0.9197 
O:  0.0896  0.2729  0.5838 
O:  0.5771  0.2385  0.0803 
O:  0.9104  0.7271  0.4162 
Atom type 

We have listed here the reduced coordinates of all the atoms in the primitive unit cell.
It is enough to know only the position of the atoms from the assymetrical unit cell and then use the symmetry to build the whole crystal structure.

Visualization of the crystal structure: 

Size:

  
Nx:  Ny:  Nz:    
You can define the size of the supercell to be displayed in the jmol panel as integer translations along the three crys­tallo­gra­phic axis.
Please note that the structure is represented using the pri­mi­tive cell, and not the conventional one.
     

Powder Raman 

Powder Raman spectrum

The intensity of the Raman peaks is computed within the density-functional perturbation theory. The intensity depends on the temperature (for now fixed at 300K), frequency of the input laser (for now fixed at 21834 cm-1, frequency of the phonon mode and the Raman tensor. The Raman tensor represents the derivative of the dielectric tensor during the atomic displacement that corresponds to the phonon vibration. The Raman tensor is related to the polarizability of a specific phonon mode.

Horizontal:
Xmin:
Xmax:
Vertical:
Ymin:
Ymax:
 
Choose the polarization of the lasers.
I ∥ 
I ⊥ 
I Total 

Data about the phonon modes

Frequency of the transverse (TO) and longitudinal (LO) phonon modes in the zone-center. The longitudinal modes are computed along the three cartesian directions. You can visualize the atomic displacement pattern corresponding to each phonon by clicking on the appropriate cell in the table below.

1
0
0
0
0
2
0
0
0
0
3
0
0
0
0
4
295
295
295
295
7.310e+38
4.1
4.113e+38
2.3
1.142e+39
6.4
5
304
304
305
304
6
352
352
352
352
2.296e+38
1.3
6.548e+37
0.4
2.951e+38
1.7
7
361
361
361
361
8
374
375
375
376
9
381
381
381
381
10
384
384
384
384
1.044e+38
0.6
7.831e+37
0.4
1.827e+38
1.0
11
392
392
392
392
1.030e+38
0.6
3.451e+37
0.2
1.375e+38
0.8
12
405
405
406
406
13
424
424
424
424
8.554e+38
4.8
7.720e+37
0.4
9.326e+38
5.2
14
427
427
427
427
3.028e+37
0.2
3.897e+37
0.2
6.925e+37
0.4
15
439
441
444
439
16
447
447
450
450
17
465
465
465
465
4.612e+39
25.9
1.136e+38
0.6
4.726e+39
26.5
18
490
491
492
490
19
495
495
496
495
20
496
496
499
496
3.248e+38
1.8
3.854e+38
2.2
7.102e+38
4.0
21
516
516
516
516
22
516
516
526
516
2.177e+38
1.2
7.264e+37
0.4
2.904e+38
1.6
23
531
532
537
535
24
554
555
555
555
25
555
563
555
555
1.439e+39
8.1
1.119e+38
0.6
1.550e+39
8.7
26
563
565
563
563
8.595e+38
4.8
7.500e+37
0.4
9.345e+38
5.2
27
578
579
581
578
28
581
581
583
581
3.240e+39
18.2
1.862e+38
1.0
3.427e+39
19.2
29
589
597
595
591
30
597
598
597
597
1.940e+38
1.1
4.335e+37
0.2
2.373e+38
1.3
31
599
609
607
603
32
609
611
609
609
2.873e+39
16.1
1.736e+38
1.0
3.046e+39
17.1
33
611
626
612
612
34
631
642
635
633
35
642
648
642
642
1.079e+39
6.1
3.692e+38
2.1
1.449e+39
8.1
36
652
652
652
652
5.787e+38
3.2
4.705e+38
2.6
1.049e+39
5.9
37
658
665
658
658
38
666
666
666
666
2.555e+38
1.4
2.631e+38
1.5
5.186e+38
2.9
39
669
672
672
670
40
672
679
679
672
4.949e+39
27.8
3.294e+38
1.8
5.279e+39
29.6
41
679
683
688
679
3.136e+39
17.6
5.575e+38
3.1
3.694e+39
20.7
42
707
707
707
707
2.430e+39
13.6
6.968e+37
0.4
2.500e+39
14.0
43
710
714
711
732
44
732
738
735
741
45
744
745
746
747
46
747
747
747
753
1.590e+39
8.9
1.106e+39
6.2
2.696e+39
15.1
47
753
754
753
754
48
754
766
754
768
4.994e+38
2.8
3.557e+38
2.0
8.552e+38
4.8
49
769
769
769
769
7.087e+37
0.4
1.053e+38
0.6
1.762e+38
1.0
50
777
783
778
783
51
783
797
783
798
2.230e+38
1.3
2.919e+38
1.6
5.149e+38
2.9
52
799
799
799
805
53
805
812
812
812
54
812
822
826
829
6.193e+39
34.8
1.930e+37
0.1
6.212e+39
34.9
55
829
842
844
845
56
845
845
845
847
1.765e+40
99.1
1.617e+38
0.9
1.781e+40
100.0
57
849
871
871
863
58
872
882
882
882
59
882
893
890
893
7.189e+37
0.4
4.449e+37
0.2
1.164e+38
0.7
60
893
906
893
909
4.987e+39
28.0
8.037e+37
0.5
5.068e+39
28.5
61
909
914
916
916
62
916
916
925
932
1.034e+38
0.6
1.322e+38
0.7
2.356e+38
1.3
63
932
933
934
940
64
941
954
960
968
65
969
976
976
976
66
976
984
984
988
1.638e+39
9.2
1.545e+37
0.1
1.654e+39
9.3
67
988
988
988
991
1.910e+39
10.7
1.067e+38
0.6
2.017e+39
11.3
68
992
1025
1025
1025
69
1025
1033
1030
1036
3.536e+38
2.0
6.172e+37
0.3
4.153e+38
2.3
70
1037
1046
1044
1043
71
1047
1095
1095
1095
72
1095
1153
1143
1128
5.029e+38
2.8
8.131e+38
4.6
1.316e+39
7.4
No.  Char.  ω TO  ω LOx  ω LOy  ω LOz  I ∥  I ⊥  I Total 
You can define the size of the supercell for the visualization of the vibration.
Nx: 
Ny: 
Nz: 
Normalized
Raw
Options for intensity.