-    DIOPSIDE     -    CaMg(SiO3)2

Theoretical atomic positions and lattice parameters at experimental volum from AMCSD 

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:  15  C2/c 
Lattice parameters (Å):  9.7483  8.9246  5.2505 
Angles (°):  90  105.882  90 

Symmetry (theoretical): 

Space group:  15  C2/c 
Lattice parameters (Å):  6.6125  6.6125  5.2461 
Angles (°):  78.28  101.71  95.02 

Cell contents: 

Number of atoms:  20 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

Ca:  0.3031  0.3031  0.2500 
Mg:  0.9083  0.9083  0.2500 
Si:  0.3786  0.8081  0.2267 
O:  0.2011  0.9701  0.1402 
O:  0.6101  0.8873  0.3125 
O:  0.3646  0.6657  0.9953 
Si:  0.8081  0.3786  0.2733 
O:  0.9701  0.2011  0.3598 
O:  0.8873  0.6101  0.1875 
O:  0.6657  0.3646  0.5047 
Ca:  0.6969  0.6969  0.7500 
Mg:  0.0917  0.0917  0.7500 
Si:  0.6214  0.1919  0.7733 
O:  0.7989  0.0299  0.8598 
O:  0.3899  0.1127  0.6875 
O:  0.6354  0.3343  0.0047 
Si:  0.1919  0.6214  0.7267 
O:  0.0299  0.7989  0.6402 
O:  0.1127  0.3899  0.8125 
O:  0.3343  0.6354  0.4953 
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
ac
0
0
0
0
2
ac
0
0
0
0
3
ac
0
0
0
0
4
Bg
107
107
107
107
1.820e+38
0.3
2.869e+38
0.5
4.689e+38
0.8
5
Bu
127
134
127
130
6
Ag
134
155
134
134
2.009e+39
3.3
1.068e+39
1.7
3.077e+39
5.0
7
Bg
155
157
155
155
4.038e+38
0.7
6.006e+38
1.0
1.004e+39
1.6
8
Bu
166
167
166
166
9
Ag
176
176
176
176
3.949e+38
0.6
7.340e+37
0.1
4.683e+38
0.8
10
Bg
189
189
189
189
8.382e+38
1.4
9.038e+38
1.5
1.742e+39
2.8
11
Au
216
216
223
216
12
Bg
225
225
225
225
1.049e+39
1.7
1.769e+39
2.9
2.818e+39
4.6
13
Ag
230
230
230
230
2.229e+38
0.4
1.857e+38
0.3
4.086e+38
0.7
14
Au
232
232
251
232
15
Ag
251
251
252
251
1.094e+39
1.8
1.282e+38
0.2
1.223e+39
2.0
16
Bu
266
266
266
266
17
Bu
288
288
288
293
18
Bu
295
295
295
295
19
Bg
295
303
295
295
3.385e+38
0.5
5.436e+38
0.9
8.821e+38
1.4
20
Ag
303
304
303
303
3.846e+39
6.2
9.629e+38
1.6
4.808e+39
7.8
21
Au
304
310
304
304
22
Ag
320
320
320
320
1.360e+40
22.0
2.996e+38
0.5
1.389e+40
22.5
23
Bg
322
322
322
322
1.328e+38
0.2
2.085e+38
0.3
3.413e+38
0.6
24
Bu
322
324
322
323
25
Au
324
342
334
324
26
Bg
349
349
349
349
1.808e+39
2.9
1.292e+39
2.1
3.100e+39
5.0
27
Bg
350
350
350
350
1.727e+39
2.8
2.159e+39
3.5
3.886e+39
6.3
28
Bg
361
361
361
361
4.441e+38
0.7
7.030e+38
1.1
1.147e+39
1.9
29
Au
362
362
362
362
30
Bu
368
378
368
372
31
Ag
378
394
378
378
1.224e+40
19.8
1.693e+39
2.7
1.394e+40
22.6
32
Bg
394
401
394
394
1.790e+39
2.9
1.923e+39
3.1
3.713e+39
6.0
33
Au
401
418
407
401
34
Bu
420
420
420
420
35
Bu
440
443
440
456
36
Bg
456
456
456
457
7.714e+38
1.2
8.237e+38
1.3
1.595e+39
2.6
37
Au
457
457
480
489
38
Au
489
489
492
492
39
Ag
492
492
492
493
8.334e+38
1.3
8.279e+38
1.3
1.661e+39
2.7
40
Au
493
493
495
493
8.526e+35
0.0
7.919e+35
0.0
1.645e+36
0.0
41
Bu
495
498
498
498
42
Bg
498
511
511
511
3.620e+38
0.6
5.204e+38
0.8
8.824e+38
1.4
43
Ag
511
511
544
544
2.765e+39
4.5
1.605e+38
0.3
2.925e+39
4.7
44
Bg
544
544
553
571
1.636e+39
2.6
1.895e+39
3.1
3.531e+39
5.7
45
Bu
610
623
610
610
46
Ag
643
643
643
643
3.465e+40
56.1
1.591e+38
0.3
3.481e+40
56.3
47
Au
647
647
652
647
48
Bg
683
683
683
683
4.731e+38
0.8
7.446e+38
1.2
1.218e+39
2.0
49
Bu
821
822
821
822
50
Ag
822
827
822
882
2.476e+39
4.0
6.789e+38
1.1
3.155e+39
5.1
51
Au
882
882
884
884
52
Bg
884
884
898
925
2.277e+38
0.4
3.569e+38
0.6
5.845e+38
0.9
53
Au
925
925
937
925
54
Bu
937
938
938
938
55
Bg
938
971
964
943
5.479e+37
0.1
7.881e+37
0.1
1.336e+38
0.2
56
Ag
983
983
983
983
6.012e+40
97.3
1.656e+39
2.7
6.177e+40
100.0
57
Ag
1025
1025
1025
1025
3.027e+39
4.9
2.277e+39
3.7
5.304e+39
8.6
58
Bg
1027
1027
1027
1027
3.054e+38
0.5
3.902e+38
0.6
6.956e+38
1.1
59
Bu
1030
1046
1030
1046
60
Au
1046
1100
1104
1056
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.