-    MONTICELLITE     -    MgCaSiO4

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:  62  Pbnm 
Lattice parameters (Å):  2.5512  5.8765  3.3767 
Angles (°):  90.0  90.0  90.0 

Symmetry (theoretical): 

Space group:  62  Pbnm 
Lattice parameters (Å):  4.7976  11.1791  6.3696 
Angles (°):  90.0  90.0  90.0 

Cell contents: 

Number of atoms:  28 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

Mg:  0.0000  0.0000  0.0000 
Ca:  0.9786  0.2750  0.2500 
Si:  0.4097  0.0790  0.2500 
O:  0.7453  0.0763  0.2500 
O:  0.2506  0.4490  0.2500 
O:  0.2710  0.1442  0.0460 
Mg:  0.5000  0.5000  0.0000 
Ca:  0.4786  0.2250  0.7500 
Si:  0.9097  0.4210  0.7500 
O:  0.2453  0.4237  0.7500 
O:  0.7506  0.0510  0.7500 
O:  0.7710  0.3558  0.9540 
Mg:  0.0000  0.0000  0.5000 
Ca:  0.0214  0.7250  0.7500 
Si:  0.5903  0.9210  0.7500 
O:  0.2547  0.9237  0.7500 
O:  0.7494  0.5510  0.7500 
O:  0.7290  0.8558  0.5460 
Mg:  0.5000  0.5000  0.5000 
Ca:  0.5214  0.7750  0.2500 
Si:  0.0903  0.5790  0.2500 
O:  0.7547  0.5763  0.2500 
O:  0.2494  0.9490  0.2500 
O:  0.2290  0.6442  0.4540 
O:  0.7290  0.8558  0.9540 
O:  0.2290  0.6442  0.0460 
O:  0.2710  0.1442  0.4540 
O:  0.7710  0.3558  0.5460 
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
Au
97
97
97
97
5
B2u
119
119
122
119
6
B2g
140
140
140
140
1.943e+37
0.0
2.671e+37
0.0
4.614e+37
0.1
7
A1g
145
145
145
145
5.303e+38
1.0
1.122e+38
0.2
6.424e+38
1.2
8
B1g
163
163
163
163
2.968e+38
0.5
4.081e+38
0.7
7.050e+38
1.3
9
B3u
169
170
169
169
10
A1g
170
171
170
170
5.793e+38
1.0
9.175e+37
0.2
6.711e+38
1.2
11
Au
173
173
173
173
12
B1u
174
174
174
190
13
Au
199
199
199
199
14
B3u
200
200
200
200
15
B1u
201
201
201
203
16
B2u
203
203
208
213
17
B1g
213
213
213
213
18
B3g
222
222
222
222
3.610e+37
0.1
4.964e+37
0.1
8.574e+37
0.2
19
B1u
238
238
238
244
20
B2g
244
244
244
244
2.495e+38
0.4
3.430e+38
0.6
5.925e+38
1.1
21
B3g
246
246
246
246
2.757e+38
0.5
3.792e+38
0.7
6.549e+38
1.2
22
B3u
247
249
247
247
23
A1g
257
257
257
257
3.327e+39
6.0
1.417e+38
0.3
3.469e+39
6.2
24
B2g
258
258
258
258
1.308e+36
0.0
1.799e+36
0.0
3.107e+36
0.0
25
B1g
264
264
264
264
5.860e+37
0.1
8.057e+37
0.1
1.392e+38
0.3
26
Au
264
264
264
264
27
B3g
270
270
270
270
1.846e+37
0.0
2.539e+37
0.0
4.385e+37
0.1
28
A1g
282
282
282
282
9.821e+38
1.8
2.842e+37
0.1
1.010e+39
1.8
29
B2u
287
287
293
287
30
B3u
293
297
297
293
31
B2u
297
306
303
297
32
B1u
306
307
306
306
33
B2u
307
308
308
307
34
B1g
308
308
308
308
1.744e+37
0.0
2.398e+37
0.0
4.143e+37
0.1
35
B3u
308
313
313
308
36
Ag
313
313
313
313
5.259e+37
0.1
1.172e+37
0.0
6.432e+37
0.1
37
Ag
313
325
330
313
1.775e+39
3.2
3.956e+38
0.7
2.170e+39
3.9
38
B2g
330
330
330
330
3.008e+37
0.1
4.136e+37
0.1
7.144e+37
0.1
39
B3g
333
333
333
333
5.968e+37
0.1
8.206e+37
0.1
1.417e+38
0.3
40
B1g
343
343
343
343
41
B1u
360
360
360
361
42
Au
362
362
362
362
43
B3u
369
375
369
369
44
B2u
375
389
390
375
45
Au
390
390
399
390
46
B1u
399
399
404
404
47
A1g
404
404
406
406
3.141e+38
0.6
2.343e+38
0.4
5.484e+38
1.0
48
B1g
406
406
406
406
2.035e+39
3.7
2.966e+39
5.3
5.001e+39
9.0
49
B3g
406
406
406
422
5.778e+38
1.0
6.271e+38
1.1
1.205e+39
2.2
50
B2g
422
422
422
431
1.136e+39
2.0
1.562e+39
2.8
2.699e+39
4.9
51
B2u
431
431
439
438
52
B1u
439
439
440
440
53
Au
440
440
445
445
54
B3u
445
451
450
456
55
B3u
463
468
463
463
56
B2u
468
499
469
468
57
B1u
499
505
499
505
58
Au
505
511
505
511
59
B2u
511
514
521
521
60
B3u
521
522
527
527
61
A1g
527
527
545
543
1.012e+39
1.8
7.520e+38
1.4
1.764e+39
3.2
62
B1g
550
550
550
550
3.309e+38
0.6
4.549e+38
0.8
7.858e+38
1.4
63
B2g
557
557
557
557
4.329e+38
0.8
5.953e+38
1.1
1.028e+39
1.8
64
B3g
564
564
564
564
7.898e+37
0.1
1.086e+38
0.2
1.876e+38
0.3
65
B3u
575
577
575
575
66
A1g
577
582
577
577
4.929e+39
8.9
7.449e+38
1.3
5.674e+39
10.2
67
B2u
582
586
583
582
68
B1g
586
610
586
586
1.523e+38
0.3
2.095e+38
0.4
3.618e+38
0.7
69
A1g
801
801
801
801
5.463e+40
98.2
9.740e+38
1.8
5.561e+40
100.0
70
B3u
806
806
806
806
71
B2u
806
807
808
806
72
B1g
810
810
810
810
3.257e+38
0.6
4.479e+38
0.8
7.736e+38
1.4
73
A1g
829
829
829
829
2.658e+40
47.8
2.927e+39
5.3
2.950e+40
53.1
74
B1g
834
834
834
834
5.988e+38
1.1
8.233e+38
1.5
1.422e+39
2.6
75
B1u
853
853
853
859
76
B2u
859
859
860
860
77
B2g
860
860
873
873
2.324e+38
0.4
3.195e+38
0.6
5.519e+38
1.0
78
Au
873
873
882
882
79
B3g
882
882
924
924
3.877e+39
7.0
5.331e+39
9.6
9.209e+39
16.6
80
A1g
924
924
931
931
5.453e+39
9.8
3.212e+39
5.8
8.665e+39
15.6
81
B1g
931
931
931
931
1.256e+38
0.2
1.727e+38
0.3
2.983e+38
0.5
82
B3u
931
936
933
939
83
B3u
939
939
939
939
84
B2u
939
1021
947
953
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.