-    TETRAROOSEVELTITE     -    BiAsO4

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:  88  I4_1/a 
Lattice parameters (Å):  5.0800  5.0800  11.7000 
Angles (°):  90  90  90 

Symmetry (theoretical): 

Space group:  88  I4_1/a 
Lattice parameters (Å):  6.6503  6.6503  6.6503 
Angles (°):  135.85  135.85  64.19 

Cell contents: 

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

Atomic positions (theoretical):

Bi:  0.5000  0.5000  0.0000 
As:  0.0000  0.0000  0.0000 
O:  0.2285  0.3290  0.3971 
O:  0.9319  0.8314  0.6029 
Bi:  0.2500  0.7500  0.5000 
As:  0.7500  0.2500  0.5000 
O:  0.0790  0.1819  0.6005 
O:  0.5814  0.4785  0.3995 
O:  0.5215  0.9210  0.1029 
O:  0.8181  0.4186  0.8971 
O:  0.6710  0.0681  0.8995 
O:  0.1686  0.7715  0.1005 
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.

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
0
0
0
0
2
0
0
0
0
3
0
0
0
0
4
89
89
89
89
1.205e+39
0.1
1.542e+39
0.1
2.747e+39
0.2
5
89
89
89
89
1.205e+39
0.1
1.772e+39
0.1
2.977e+39
0.2
6
103
103
103
105
7
105
105
105
137
1.076e+40
0.6
1.257e+40
0.7
2.333e+40
1.3
8
137
137
137
137
9
137
169
169
161
10
169
169
169
169
4.572e+39
0.3
4.900e+39
0.3
9.473e+39
0.5
11
169
170
170
169
4.572e+39
0.3
7.674e+39
0.4
1.225e+40
0.7
12
174
174
174
174
1.008e+40
0.6
1.386e+40
0.8
2.393e+40
1.3
13
195
195
195
195
14
195
234
234
195
15
234
235
235
234
4.022e+40
2.2
4.124e+39
0.2
4.434e+40
2.5
16
262
262
262
262
17
266
266
266
282
18
282
282
282
282
2.910e+39
0.2
4.542e+39
0.3
7.451e+39
0.4
19
282
282
282
318
2.910e+39
0.2
3.461e+39
0.2
6.370e+39
0.4
20
354
354
354
354
1.789e+41
10.0
1.286e+41
7.2
3.075e+41
17.2
21
362
362
362
362
22
362
363
363
362
23
363
410
410
363
3.367e+40
1.9
3.834e+40
2.1
7.201e+40
4.0
24
410
410
410
410
8.412e+40
4.7
9.186e+40
5.1
1.760e+41
9.8
25
410
434
434
410
8.412e+40
4.7
1.395e+41
7.8
2.236e+41
12.5
26
434
437
437
454
27
454
454
454
469
1.167e+41
6.5
1.595e+41
8.9
2.762e+41
15.4
28
469
469
469
500
29
719
719
719
719
1.045e+41
5.8
1.422e+41
7.9
2.467e+41
13.8
30
740
740
740
740
31
740
743
743
740
32
743
758
758
758
33
758
758
758
758
6.796e+40
3.8
1.115e+41
6.2
1.795e+41
10.0
34
758
786
786
786
6.796e+40
3.8
7.537e+40
4.2
1.433e+41
8.0
35
786
793
793
793
36
793
858
858
825
1.790e+42
100.0
8.344e+37
0.0
1.790e+42
100.0
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.