-    SPODUMENE     -    LiAlSi2O6

The crystal structure is fully relaxed (both unit cell parameters and atomic positions under symmetry constraints) starting from an experimental structure similar to the one reported in 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):  9.4628  8.3882  5.2186 
Angles (°):  90.0  110.2  90.0 

Symmetry (theoretical): 

Space group:  15  C2/c 
Lattice parameters (Å):  6.2451  6.2451  5.1499 
Angles (°):  74.7  105.3  97.4 

Cell contents: 

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

Atomic positions (theoretical):

Li:  0.2717  0.2717  0.2500 
Al:  0.9083  0.9083  0.2500 
Si:  0.3881  0.8009  0.2596 
O:  0.1924  0.9752  0.1429 
O:  0.6342  0.9045  0.2973 
O:  0.3369  0.6242  0.0689 
Si:  0.8009  0.3881  0.2404 
O:  0.9752  0.1924  0.3571 
O:  0.9045  0.6342  0.2027 
O:  0.6242  0.3369  0.4311 
Li:  0.7283  0.7283  0.7500 
Al:  0.0917  0.0917  0.7500 
Si:  0.6119  0.1991  0.7404 
O:  0.8076  0.0248  0.8571 
O:  0.3658  0.0955  0.7027 
O:  0.6631  0.3758  0.9311 
Si:  0.1991  0.6119  0.7596 
O:  0.0248  0.8076  0.6429 
O:  0.0955  0.3658  0.7973 
O:  0.3758  0.6631  0.5689 
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
121
121
121
121
3.931e+38
1.0
4.859e+38
1.2
8.790e+38
2.2
5
Bu
123
124
123
132
6
Ag
132
132
132
134
1.413e+39
3.5
7.897e+38
1.9
2.202e+39
5.4
7
Bu
174
179
174
179
8
Ag
179
180
179
217
9.518e+38
2.3
6.865e+38
1.7
1.638e+39
4.0
9
Au
217
217
221
221
10
Bg
221
221
233
233
5.997e+38
1.5
7.719e+38
1.9
1.372e+39
3.4
11
Bg
235
235
235
235
4.910e+38
1.2
7.496e+38
1.8
1.241e+39
3.1
12
Ag
250
250
250
250
1.334e+39
3.3
1.489e+39
3.7
2.823e+39
7.0
13
Bg
253
253
253
253
8.704e+38
2.1
1.197e+39
2.9
2.067e+39
5.1
14
Bu
276
277
276
290
15
Au
290
290
298
293
16
Ag
298
298
302
298
5.424e+39
13.4
6.091e+37
0.2
5.484e+39
13.5
17
Bg
302
302
302
302
2.589e+39
6.4
3.786e+39
9.3
6.374e+39
15.7
18
Bu
309
310
309
309
19
Au
314
314
325
314
20
Bg
325
325
327
325
3.325e+38
0.8
4.054e+38
1.0
7.379e+38
1.8
21
Bu
327
331
329
327
22
Ag
331
331
331
331
1.308e+39
3.2
1.006e+39
2.5
2.314e+39
5.7
23
Au
335
335
340
335
24
Ag
347
347
347
347
1.681e+40
41.4
5.436e+38
1.3
1.736e+40
42.8
25
Bu
355
358
355
356
26
Bg
358
375
358
358
4.187e+38
1.0
6.794e+38
1.7
1.098e+39
2.7
27
Bg
375
387
375
375
3.970e+38
1.0
6.518e+38
1.6
1.049e+39
2.6
28
Bu
388
391
388
389
29
Ag
391
399
391
391
8.153e+39
20.1
9.509e+38
2.3
9.104e+39
22.4
30
Au
399
403
399
399
31
Bg
422
422
422
422
5.558e+38
1.4
5.909e+38
1.5
1.147e+39
2.8
32
Bu
443
444
443
447
33
Au
447
447
450
450
34
Ag
450
450
450
467
5.391e+39
13.3
2.038e+36
0.0
5.393e+39
13.3
35
Bu
474
477
474
477
36
Au
477
506
506
513
37
Ag
513
513
513
523
6.450e+39
15.9
1.398e+38
0.3
6.589e+39
16.2
38
Au
523
523
531
531
39
Bg
531
531
544
544
3.452e+38
0.9
5.806e+38
1.4
9.257e+38
2.3
40
Bg
544
544
548
561
6.333e+38
1.6
6.948e+38
1.7
1.328e+39
3.3
41
Au
561
561
581
581
42
Ag
581
581
613
600
6.390e+39
15.7
1.491e+38
0.4
6.539e+39
16.1
43
Bg
613
613
623
613
2.162e+38
0.5
2.297e+38
0.6
4.459e+38
1.1
44
Bu
623
657
633
623
45
Bu
657
670
657
658
46
Ag
697
697
697
697
3.954e+40
97.5
1.028e+39
2.5
4.057e+40
100.0
47
Bg
775
775
775
775
6.469e+38
1.6
9.446e+38
2.3
1.592e+39
3.9
48
Au
780
780
780
780
49
Au
851
851
859
851
50
Bu
862
878
862
877
51
Bg
878
945
878
878
1.971e+38
0.5
2.154e+38
0.5
4.124e+38
1.0
52
Ag
969
969
969
969
5.838e+39
14.4
2.941e+39
7.3
8.780e+39
21.6
53
Bu
1011
1014
1011
1014
54
Ag
1014
1044
1014
1056
3.949e+39
9.7
9.008e+38
2.2
4.850e+39
12.0
55
Bg
1056
1056
1056
1067
2.405e+38
0.6
2.632e+38
0.6
5.037e+38
1.2
56
Au
1067
1067
1071
1072
57
Ag
1072
1072
1072
1073
1.816e+40
44.8
1.739e+39
4.3
1.990e+40
49.1
58
Au
1079
1079
1080
1079
59
Bu
1080
1093
1093
1093
60
Bg
1093
1130
1206
1146
5.784e+38
1.4
9.374e+38
2.3
1.516e+39
3.7
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.