-    SEIFERTITE     -    SiO2

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:  60   Pbcn  
Lattice parameters (Å):  2.1680  2.6703  2.3784 
Angles (°):  90  90  90  

Symmetry (theoretical): 

Space group:  60   Pbcn  
Lattice parameters (Å):  4.0315  4.9803  4.4419 
Angles (°):  90  90  90 

Cell contents: 

Number of atoms:  12  
Number of atom types:  2  
Chemical composition:  0 

Atomic positions (theoretical):

Si:  0.0000  0.1524  0.2500 
O:  0.7316  0.6174  0.9197 
Si:  0.5000  0.3476  0.7500 
O:  0.7684  0.8826  0.4197 
O:  0.2684  0.6174  0.5803 
O:  0.2316  0.8826  0.0803 
Si:  0.0000  0.8476  0.7500 
O:  0.2684  0.3826  0.0803 
Si:  0.5000  0.6524  0.2500 
O:  0.2316  0.1174  0.5803 
O:  0.7316  0.3826  0.4197 
O:  0.7684  0.1174  0.9197 
Atom type  X  Y  Z 

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.

Choose the polarization of the lasers.

I ∥ 
I ⊥ 
I Total 
Horizontal:
Xmin:
Xmax:
Vertical:
Ymin:
Ymax:
 

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
B3g
354
354
354
354
3.984e+36
0.0
5.479e+36
0.1
9.463e+36
0.1
5
A1g
377
377
377
377
8.558e+39
81.7
1.591e+38
1.5
8.717e+39
83.3
6
B1u
378
378
378
381
7
B3g
400
400
400
400
2.089e+37
0.2
2.872e+37
0.3
4.960e+37
0.5
8
B1g
401
401
401
401
2.216e+38
2.1
3.047e+38
2.9
5.264e+38
5.0
9
B3u
450
458
450
450
10
B3u
458
491
458
458
11
B1g
491
493
491
491
1.355e+38
1.3
1.863e+38
1.8
3.217e+38
3.1
12
B2u
493
499
499
493
13
Au
499
505
505
499
14
B1u
505
509
509
509
15
A1g
509
522
531
531
1.039e+40
99.2
8.154e+37
0.8
1.047e+40
100.0
16
B1g
531
531
541
535
3.002e+38
2.9
4.128e+38
3.9
7.129e+38
6.8
17
B2g
541
541
548
541
1.423e+38
1.4
1.956e+38
1.9
3.379e+38
3.2
18
Au
548
548
559
548
19
A1g
559
559
608
559
1.554e+39
14.8
7.529e+37
0.7
1.629e+39
15.6
20
B3g
608
608
612
608
8.305e+37
0.8
1.142e+38
1.1
1.972e+38
1.9
21
B1u
621
621
621
642
22
B2g
642
642
642
645
2.222e+38
2.1
3.055e+38
2.9
5.277e+38
5.0
23
B1g
645
645
645
650
3.578e+36
0.0
4.920e+36
0.0
8.498e+36
0.1
24
B3u
650
678
650
678
25
B2u
678
693
693
693
26
Au
693
715
731
726
27
B2g
731
731
732
731
1.461e+39
14.0
2.010e+39
19.2
3.471e+39
33.2
28
B3u
732
741
741
732
29
B3g
741
751
751
741
2.758e+38
2.6
3.792e+38
3.6
6.550e+38
6.3
30
B1u
751
793
793
793
31
A1g
793
793
793
793
3.723e+39
35.6
1.029e+36
0.0
3.724e+39
35.6
32
Au
793
798
797
798
33
B2u
798
853
853
853
34
B3g
853
880
880
880
4.922e+38
4.7
6.768e+38
6.5
1.169e+39
11.2
35
B1g
880
924
924
924
3.588e+38
3.4
4.934e+38
4.7
8.522e+38
8.1
36
B2g
924
1017
1006
1035
1.955e+39
18.7
2.689e+39
25.7
4.644e+39
44.4
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.