-    CRISTOBALITE X-I     -    SiO2

2x1x1 super structure. The crystal structure is fully relaxed (both unit cell parameters and atomic positions under symmetry constraints) at 10GPa. 

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 14  Theo P2_1/n 
Lattice parameters (Å):  6.7500  4.0633  6.8344 
Angles (°):  90  90  90 

Symmetry (theoretical): 

Space group:  Theo 14  Theo P2_1/n 
Lattice parameters (Å):  12.8731  3.8829  6.6716 
Angles (°): 

Cell contents: 

Number of atoms:  48 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

Si:  0.2508  0.0002  0.5013 
Si:  0.9959  0.4984  0.0008 
Si:  0.1787  0.9983  0.1178 
Si:  0.0697  0.5021  0.3759 
Si:  0.3209  0.0021  0.8831 
Si:  0.4325  0.5006  0.6255 
Si:  0.1358  0.4969  0.7584 
Si:  0.3632  0.5050  0.2441 
O:  0.1660  0.2247  0.3323 
O:  0.0822  0.7325  0.1664 
O:  0.3355  0.7743  0.6703 
O:  0.4183  0.2599  0.8346 
O:  0.2336  0.2345  0.7120 
O:  0.0223  0.7200  0.7949 
O:  0.2660  0.7656  0.2897 
O:  0.4767  0.2794  0.2056 
O:  0.1517  0.7314  0.5458 
O:  0.1027  0.2538  0.9567 
O:  0.3501  0.2688  0.4569 
O:  0.3961  0.7446  0.0439 
O:  0.2114  0.7614  0.9210 
O:  0.0439  0.2813  0.5813 
O:  0.2882  0.2385  0.0808 
O:  0.4549  0.7269  0.4164 
Si:  0.7458  0.0019  0.5004 
Si:  0.5008  0.4992  0.0012 
Si:  0.6812  0.9959  0.1184 
Si:  0.5670  0.4996  0.3753 
Si:  0.8192  0.9974  0.8748 
Si:  0.9308  0.5047  0.6174 
Si:  0.6359  0.4938  0.7570 
Si:  0.8852  0.0043  0.2589 
O:  0.6647  0.2332  0.3306 
O:  0.5834  0.7400  0.1675 
O:  0.8331  0.7666  0.6659 
O:  0.9155  0.2682  0.8306 
O:  0.7328  0.2327  0.7090 
O:  0.5233  0.7198  0.7959 
O:  0.7721  0.7810  0.2951 
O:  0.9824  0.2669  0.2099 
O:  0.6485  0.7319  0.5441 
O:  0.6054  0.2527  0.9577 
O:  0.8536  0.2489  0.4567 
O:  0.8997  0.7679  0.0450 
O:  0.7121  0.7514  0.9187 
O:  0.5444  0.2728  0.5844 
O:  0.7939  0.2191  0.0814 
O:  0.9623  0.7491  0.4196 
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
0
172
172
172
5
0
198
198
198
6
0
203
203
203
7
0
204
204
204
8
0
295
295
295
9
0
307
307
307
10
0
324
324
324
11
0
327
327
327
12
0
332
332
332
13
0
347
347
347
14
0
352
352
352
15
0
355
355
355
16
0
362
362
362
17
0
365
365
365
18
0
377
377
377
19
0
379
379
379
20
0
384
384
384
21
0
390
390
390
22
0
397
397
397
23
0
399
399
399
24
0
412
412
412
25
0
417
417
417
26
0
421
421
422
27
0
423
424
423
28
0
427
428
428
29
0
430
432
430
30
0
435
435
435
31
0
440
441
441
32
0
441
444
441
33
0
447
448
447
34
0
455
457
455
35
0
471
471
471
36
0
486
486
487
37
0
490
490
490
38
0
493
495
492
39
0
496
499
496
40
0
501
506
501
41
0
508
510
508
42
0
517
516
517
43
0
520
520
520
44
0
522
523
522
45
0
524
527
524
46
0
530
530
531
47
0
532
532
532
48
0
543
543
543
49
0
557
557
557
50
0
561
558
558
51
0
567
565
565
52
0
570
569
569
53
0
575
575
576
54
0
579
577
578
55
0
587
581
579
56
0
593
593
588
57
0
597
593
593
58
0
599
601
597
59
0
609
606
603
60
0
611
611
610
61
0
611
611
611
62
0
619
614
613
63
0
624
621
620
64
0
630
630
630
65
0
632
632
630
66
0
640
634
634
67
0
641
641
641
68
0
645
644
643
69
0
648
648
648
70
0
650
650
648
71
0
651
651
651
72
0
654
652
652
73
0
658
657
657
74
0
661
660
659
75
0
662
662
662
76
0
669
670
669
77
0
672
671
671
78
0
674
673
673
79
0
681
679
677
80
0
682
681
681
81
0
688
682
682
82
0
689
690
688
83
0
690
692
691
84
0
699
700
700
85
0
705
705
704
86
0
712
713
713
87
0
714
713
719
88
0
728
720
726
89
0
731
731
731
90
0
738
734
743
91
0
744
744
747
92
0
747
747
753
93
0
755
753
757
94
0
761
757
764
95
0
765
766
767
96
0
767
768
768
97
0
770
771
780
98
0
782
785
785
99
0
789
788
789
100
0
794
789
795
101
0
796
798
797
102
0
801
802
805
103
0
807
805
810
104
0
811
811
811
105
0
815
816
815
106
0
822
820
822
107
0
822
822
822
108
0
829
830
830
109
0
833
835
835
110
0
841
842
842
111
0
847
847
847
112
0
854
854
855
113
0
865
865
862
114
0
867
868
868
115
0
876
873
875
116
0
884
884
882
117
0
887
884
887
118
0
892
890
892
119
0
897
893
898
120
0
907
904
906
121
0
916
908
915
122
0
919
917
917
123
0
926
921
930
124
0
931
931
938
125
0
939
938
941
126
0
941
948
952
127
0
953
953
956
128
0
958
961
963
129
0
966
969
968
130
0
977
981
982
131
0
983
984
984
132
0
987
989
990
133
0
992
995
995
134
0
1006
1007
1005
135
0
1009
1009
1008
136
0
1026
1026
1026
137
0
1028
1029
1029
138
0
1032
1031
1031
139
0
1040
1038
1040
140
0
1049
1048
1049
141
0
1096
1096
1096
142
0
1132
1131
1129
143
0
1135
1136
1132
144
0
1155
1142
1136
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.