-    AKERMANITE     -    Ca2MgSi2O7

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:  113  P-42_1m 
Lattice parameters (Å):  7.8338  7.8338  5.0082 
Angles (°):  90  90  90 

Symmetry (theoretical): 

Space group:  113  P-42_1m 
Lattice parameters (Å):  7.8435  7.8435  4.9958 
Angles (°):  90  90  90 

Cell contents: 

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

Atomic positions (theoretical):

Ca:  0.3336  0.1664  0.5070 
Mg:  0.0000  0.0000  0.0000 
Si:  0.1397  0.3603  0.9345 
O:  0.5000  0.0000  0.1844 
O:  0.1387  0.3613  0.2537 
O:  0.0809  0.1867  0.7885 
Ca:  0.8336  0.3336  0.4930 
Si:  0.6397  0.1397  0.0655 
O:  0.0000  0.5000  0.8156 
O:  0.6387  0.1387  0.7463 
O:  0.8133  0.0809  0.2115 
Ca:  0.1664  0.6664  0.4930 
Mg:  0.5000  0.5000  0.0000 
Si:  0.3603  0.8603  0.0655 
O:  0.3613  0.8613  0.7463 
O:  0.4191  0.6867  0.2115 
Ca:  0.6664  0.8336  0.5070 
Si:  0.8603  0.6397  0.9345 
O:  0.8613  0.6387  0.2537 
O:  0.9191  0.8133  0.7885 
O:  0.3133  0.4191  0.7885 
O:  0.6867  0.5809  0.7885 
O:  0.1867  0.9191  0.2115 
O:  0.5809  0.3133  0.2115 
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
A2
37
37
37
37
5
E
75
75
75
75
3.749e+37
0.1
5.155e+37
0.1
8.904e+37
0.2
6
E
75
76
76
75
3.749e+37
0.1
5.155e+37
0.1
8.904e+37
0.2
7
B1
85
85
85
85
6.582e+38
1.1
4.936e+38
0.8
1.152e+39
2.0
8
A1
126
126
126
126
3.329e+38
0.6
3.401e+37
0.1
3.669e+38
0.6
9
E
129
129
129
129
3.094e+36
0.0
4.254e+36
0.0
7.348e+36
0.0
10
E
129
147
147
129
3.093e+36
0.0
4.253e+36
0.0
7.347e+36
0.0
11
B1
147
152
152
147
1.082e+38
0.2
8.116e+37
0.1
1.894e+38
0.3
12
E
158
158
158
158
8.042e+36
0.0
1.106e+37
0.0
1.910e+37
0.0
13
E
158
163
163
158
8.040e+36
0.0
1.106e+37
0.0
1.910e+37
0.0
14
E
163
163
163
163
4.695e+38
0.8
6.456e+38
1.1
1.115e+39
1.9
15
E
163
181
181
163
4.695e+38
0.8
6.456e+38
1.1
1.115e+39
1.9
16
B2
183
183
183
186
8.271e+36
0.0
1.137e+37
0.0
1.964e+37
0.0
17
E
186
186
186
186
1.686e+38
0.3
2.319e+38
0.4
4.005e+38
0.7
18
E
186
190
190
190
1.686e+38
0.3
2.318e+38
0.4
4.005e+38
0.7
19
A1
190
193
193
206
1.132e+38
0.2
7.121e+37
0.1
1.845e+38
0.3
20
B1
206
206
206
211
3.420e+38
0.6
2.565e+38
0.4
5.985e+38
1.0
21
A2
214
214
214
214
22
A1
217
217
217
217
1.894e+39
3.2
6.530e+36
0.0
1.900e+39
3.2
23
E
220
220
220
220
4.489e+38
0.8
6.172e+38
1.0
1.066e+39
1.8
24
E
220
221
221
220
4.489e+38
0.8
6.172e+38
1.0
1.066e+39
1.8
25
B2
242
242
242
242
1.719e+37
0.0
2.363e+37
0.0
4.082e+37
0.1
26
A2
243
243
243
243
27
E
260
260
260
260
2.145e+38
0.4
2.949e+38
0.5
5.094e+38
0.9
28
E
260
263
263
260
2.145e+38
0.4
2.949e+38
0.5
5.094e+38
0.9
29
B1
263
269
269
263
3.816e+37
0.1
2.862e+37
0.0
6.679e+37
0.1
30
B2
269
272
272
272
2.136e+37
0.0
2.938e+37
0.0
5.074e+37
0.1
31
A1
272
281
281
288
2.230e+38
0.4
9.043e+36
0.0
2.321e+38
0.4
32
E
305
305
305
305
2.209e+39
3.8
3.037e+39
5.2
5.246e+39
8.9
33
E
305
307
307
305
2.209e+39
3.8
3.037e+39
5.2
5.246e+39
8.9
34
A1
307
307
307
307
5.884e+37
0.1
3.881e+37
0.1
9.766e+37
0.2
35
B2
310
310
310
338
3.474e+38
0.6
4.777e+38
0.8
8.251e+38
1.4
36
E
352
352
352
352
3.050e+38
0.5
4.194e+38
0.7
7.244e+38
1.2
37
E
352
353
353
352
3.050e+38
0.5
4.194e+38
0.7
7.244e+38
1.2
38
B2
365
365
365
385
8.496e+35
0.0
1.168e+36
0.0
2.018e+36
0.0
39
E
389
389
389
389
6.446e+37
0.1
8.863e+37
0.2
1.531e+38
0.3
40
E
389
400
400
389
6.446e+37
0.1
8.863e+37
0.2
1.531e+38
0.3
41
B1
436
436
436
436
1.539e+39
2.6
1.154e+39
2.0
2.693e+39
4.6
42
A2
437
437
437
437
43
E
458
458
458
458
1.224e+36
0.0
1.683e+36
0.0
2.907e+36
0.0
44
E
458
465
465
458
1.224e+36
0.0
1.683e+36
0.0
2.907e+36
0.0
45
A1
465
471
471
465
4.013e+39
6.8
5.516e+37
0.1
4.068e+39
6.9
46
A2
471
480
480
471
47
B2
480
499
499
481
1.624e+37
0.0
2.232e+37
0.0
3.856e+37
0.1
48
E
501
501
501
501
7.975e+37
0.1
1.097e+38
0.2
1.894e+38
0.3
49
E
501
517
517
501
7.975e+37
0.1
1.097e+38
0.2
1.894e+38
0.3
50
B1
519
519
519
519
2.547e+37
0.0
1.911e+37
0.0
4.458e+37
0.1
51
E
570
570
570
570
2.973e+38
0.5
4.088e+38
0.7
7.062e+38
1.2
52
E
570
576
576
570
2.973e+38
0.5
4.088e+38
0.7
7.062e+38
1.2
53
A1
586
586
586
586
7.719e+39
13.1
1.145e+38
0.2
7.833e+39
13.3
54
E
604
604
604
604
1.043e+37
0.0
1.435e+37
0.0
2.478e+37
0.0
55
E
604
605
605
604
1.043e+37
0.0
1.435e+37
0.0
2.478e+37
0.0
56
B2
618
618
618
644
8.463e+35
0.0
1.164e+36
0.0
2.010e+36
0.0
57
A1
644
644
644
646
2.993e+40
50.9
2.161e+37
0.0
2.995e+40
50.9
58
B2
659
659
659
661
2.192e+38
0.4
3.014e+38
0.5
5.205e+38
0.9
59
E
829
829
829
829
6.782e+37
0.1
9.325e+37
0.2
1.611e+38
0.3
60
E
829
841
841
829
6.782e+37
0.1
9.325e+37
0.2
1.611e+38
0.3
61
A1
884
884
884
884
5.829e+40
99.1
5.210e+38
0.9
5.881e+40
100.0
62
B2
887
887
887
896
5.009e+38
0.9
6.888e+38
1.2
1.190e+39
2.0
63
B1
914
914
914
914
7.632e+36
0.0
5.724e+36
0.0
1.336e+37
0.0
64
E
919
919
919
919
7.646e+38
1.3
1.051e+39
1.8
1.816e+39
3.1
65
E
919
938
938
919
7.646e+38
1.3
1.051e+39
1.8
1.816e+39
3.1
66
E
945
945
945
945
1.761e+38
0.3
2.422e+38
0.4
4.183e+38
0.7
67
E
945
973
973
945
1.761e+38
0.3
2.422e+38
0.4
4.184e+38
0.7
68
A1
973
976
976
973
3.017e+39
5.1
1.941e+39
3.3
4.958e+39
8.4
69
B2
984
984
984
985
4.307e+38
0.7
5.921e+38
1.0
1.023e+39
1.7
70
A2
985
985
985
987
71
E
987
987
987
987
7.963e+36
0.0
1.095e+37
0.0
1.891e+37
0.0
72
E
987
1012
1012
1060
7.963e+36
0.0
1.095e+37
0.0
1.891e+37
0.0
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.