-    ARGUTITE     -    GeO2

Experimental structure 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:  136  P4_2/mnm 
Lattice parameters (Å):  4.3966  4.3966  2.8626 
Angles (°):  90.0  90.0  90.0 

Symmetry (theoretical): 

Space group:  136  P4_2/mnm 
Lattice parameters (Å):  4.3966  4.3966  2.8626 
Angles (°):  90.0  90.0  90.0 

Cell contents: 

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

Atomic positions (theoretical):

Ge:  0.0000  0.0000  0.0000 
O:  0.3063  0.3063  0.0000 
Ge:  0.5000  0.5000  0.5000 
O:  0.1937  0.8063  0.5000 
O:  0.6937  0.6937  0.0000 
O:  0.8063  0.1937  0.5000 
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
B1g
194
194
194
194
1.229e+39
0.9
9.218e+38
0.7
2.151e+39
1.6
5
B1u
200
200
200
200
6
E1u
293
293
293
293
7
E1u
293
339
339
293
8
E1u
341
341
341
341
9
E1u
341
447
447
341
10
A2u
447
460
460
460
11
A2g
460
463
463
484
12
E1g
484
484
484
484
3.511e+38
0.3
3.730e+38
0.3
7.241e+38
0.5
13
E1g
484
484
484
594
3.511e+38
0.3
5.925e+38
0.4
9.435e+38
0.7
14
E1u
594
594
594
594
15
E1u
594
600
600
600
16
B1u
600
641
641
641
17
A1g
641
763
763
742
1.385e+41
100.0
1.134e+36
0.0
1.385e+41
100.0
18
B2g
797
797
797
797
6.680e+39
4.8
9.185e+39
6.6
1.587e+40
11.5
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.