-    MOLYBDOMENITE     -    PbSeO3

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. Tetter norm-conserving pseudopotential for Pb. 

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:  11  P2_1/m 
Lattice parameters (Å):  4.5437  5.5137  6.6340 
Angles (°):  90  106.547  90 

Symmetry (theoretical): 

Space group:  11  P2_1/m 
Lattice parameters (Å):  4.4224  5.4651  6.4548 
Angles (°):  90  90  90 

Cell contents: 

Number of atoms:  10 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

Pb:  0.6409  0.2500  0.3019 
Se:  0.0885  0.7500  0.1543 
O:  0.6922  0.7500  0.1134 
O:  0.2011  0.5116  0.3320 
Pb:  0.3591  0.7500  0.6981 
Se:  0.9115  0.2500  0.8457 
O:  0.3078  0.2500  0.8866 
O:  0.7989  0.0116  0.6680 
O:  0.7989  0.4884  0.6680 
O:  0.2011  0.9884  0.3320 
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
53
53
53
53
3.508e+40
2.2
5.507e+40
3.5
9.015e+40
5.7
5
Ag
59
59
59
59
3.284e+40
2.1
1.872e+40
1.2
5.156e+40
3.3
6
Au
62
62
71
62
7
Ag
71
71
75
71
7.635e+40
4.8
3.129e+40
2.0
1.076e+41
6.8
8
Bg
75
75
77
75
4.026e+40
2.5
4.684e+40
3.0
8.710e+40
5.5
9
Ag
77
77
90
77
2.425e+40
1.5
1.013e+40
0.6
3.438e+40
2.2
10
Bu
90
90
97
97
11
Bu
97
119
98
119
12
Ag
119
121
119
121
1.491e+41
9.4
4.856e+39
0.3
1.539e+41
9.7
13
Au
121
141
136
141
14
Bg
141
143
141
153
2.321e+39
0.1
3.601e+39
0.2
5.922e+39
0.4
15
Au
153
153
193
169
16
Ag
193
193
204
193
2.845e+40
1.8
2.573e+40
1.6
5.418e+40
3.4
17
Bg
204
204
211
204
4.978e+40
3.1
5.761e+40
3.6
1.074e+41
6.8
18
Bu
211
242
222
219
19
Ag
341
341
341
341
1.157e+41
7.3
6.974e+40
4.4
1.854e+41
11.7
20
Au
345
345
351
345
21
Bg
354
354
354
354
1.001e+41
6.3
1.532e+41
9.7
2.534e+41
16.0
22
Bu
367
380
367
372
23
Bu
416
423
416
423
24
Ag
423
432
423
463
2.884e+40
1.8
1.665e+40
1.1
4.549e+40
2.9
25
Au
648
648
673
648
26
Bg
673
673
691
673
1.052e+40
0.7
1.261e+40
0.8
2.313e+40
1.5
27
Bu
691
698
698
698
28
Ag
698
751
737
717
2.798e+41
17.6
1.074e+41
6.8
3.873e+41
24.4
29
Bu
762
772
762
772
30
Ag
772
777
772
776
1.505e+42
94.9
8.104e+40
5.1
1.586e+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.