-    HOLLANDITE     -    KAlSi3O12

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:  87  I4/m 
Lattice parameters (Å):       
Angles (°):       

Symmetry (theoretical): 

Space group:  87  I4/m 
Lattice parameters (Å):  0.5292  0.5292  0.5292 
Angles (°):  92.35  92.35  156.60 

Cell contents: 

Number of atoms:  13 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

K:  0.5000  0.5000  0.0000 
O:  0.2032  0.1542  0.3574 
O:  0.1641  0.5412  0.7053 
Si:  0.1662  0.3502  0.5164 
O:  0.1542  0.7968  0.9510 
O:  0.5412  0.8359  0.3771 
Si:  0.3502  0.8338  0.1840 
O:  0.7968  0.8458  0.6426 
O:  0.8359  0.4588  0.2947 
Si:  0.8338  0.6498  0.4836 
O:  0.8458  0.2032  0.0490 
O:  0.4588  0.1641  0.6229 
Si:  0.6498  0.1662  0.8160 
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
0
0
0
0
2
0
0
0
0
3
0
0
0
0
4
119
119
119
123
5
165
165
165
165
6
165
180
180
165
7
219
219
219
219
1.680e+39
5.2
1.407e+39
4.3
3.088e+39
9.5
8
253
253
253
253
9
291
291
291
291
2.493e+39
7.7
3.062e+36
0.0
2.496e+39
7.7
10
320
320
320
320
5.967e+36
0.0
7.020e+36
0.0
1.299e+37
0.0
11
320
320
320
320
5.967e+36
0.0
9.390e+36
0.0
1.536e+37
0.0
12
335
335
335
335
13
335
335
335
335
14
421
421
421
421
5.830e+38
1.8
6.649e+38
2.0
1.248e+39
3.8
15
455
455
455
455
16
455
472
472
455
17
472
472
472
472
9.533e+37
0.3
1.192e+37
0.0
1.072e+38
0.3
18
485
485
485
488
19
488
488
488
497
20
529
529
529
529
1.069e+39
3.3
1.791e+39
5.5
2.859e+39
8.8
21
529
529
529
529
1.069e+39
3.3
1.148e+39
3.5
2.216e+39
6.8
22
544
544
544
544
8.076e+39
24.9
5.034e+37
0.2
8.126e+39
25.1
23
546
546
546
546
1.088e+38
0.3
1.257e+38
0.4
2.346e+38
0.7
24
578
578
578
578
25
578
578
578
578
26
578
627
627
627
27
627
627
627
627
1.099e+40
33.9
2.274e+36
0.0
1.099e+40
33.9
28
627
637
637
637
29
637
637
637
637
8.895e+37
0.3
1.488e+38
0.5
2.377e+38
0.7
30
637
652
652
652
8.895e+37
0.3
9.586e+37
0.3
1.848e+38
0.6
31
652
707
707
707
1.095e+39
3.4
1.340e+39
4.1
2.435e+39
7.5
32
707
740
740
756
6.305e+38
1.9
5.946e+38
1.8
1.225e+39
3.8
33
756
756
756
765
3.238e+40
99.8
5.220e+37
0.2
3.244e+40
100.0
34
765
765
765
765
35
765
808
808
809
36
809
809
809
879
6.506e+38
2.0
1.104e+37
0.0
6.616e+38
2.0
37
879
879
879
879
38
879
939
939
927
39
939
976
976
939
1.338e+39
4.1
1.403e+39
4.3
2.741e+39
8.5
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.