-    DOLOMITE     -    CaMg(CO3)2

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:  148  R-3 
Lattice parameters (Å):  4.8079  4.8079  16.0100 
Angles (°):  90  90  120 

Symmetry (theoretical): 

Space group:  148  R-3 
Lattice parameters (Å):  5.8682  5.8682  5.8682 
Angles (°):  48.007  48.007  48.007 

Cell contents: 

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

Atomic positions (theoretical):

Ca:  0.0000  0.0000  0.0000 
Mg:  0.5000  0.5000  0.5000 
C:  0.2421  0.2421  0.2421 
O:  0.4880  0.9582  0.2834 
O:  0.9582  0.2834  0.4880 
O:  0.2834  0.4880  0.9582 
C:  0.7579  0.7579  0.7579 
O:  0.5120  0.0418  0.7166 
O:  0.0418  0.7166  0.5120 
O:  0.7166  0.5120  0.0418 
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
Au
143
143
143
152
5
Eu
152
152
152
152
6
Eu
152
174
174
184
7
Eg
184
184
184
184
6.533e+39
7.7
5.290e+39
6.2
1.182e+40
13.9
8
Eg
184
184
184
193
6.533e+39
7.7
9.971e+39
11.7
1.650e+40
19.4
9
Ag
223
223
223
223
2.139e+38
0.3
1.475e+38
0.2
3.613e+38
0.4
10
Eu
287
287
287
287
11
Eu
287
298
298
287
12
Eg
323
323
323
323
8.536e+39
10.0
8.828e+39
10.4
1.736e+40
20.4
13
Eg
323
323
323
323
8.536e+39
10.0
1.440e+40
16.9
2.293e+40
26.9
14
Au
344
344
344
347
15
Ag
363
363
363
363
3.786e+37
0.0
2.093e+37
0.0
5.879e+37
0.1
16
Eu
386
386
386
386
17
Eu
386
393
393
386
18
Au
393
470
470
467
19
Eg
721
721
721
721
2.672e+39
3.1
2.548e+39
3.0
5.220e+39
6.1
20
Eg
721
721
721
721
2.672e+39
3.1
2.918e+39
3.4
5.590e+39
6.6
21
Eu
727
727
727
727
22
Eu
727
730
730
727
23
Au
849
849
849
857
24
Ag
857
857
857
873
5.427e+38
0.6
2.942e+36
0.0
5.456e+38
0.6
25
Ag
1109
1109
1109
1109
8.252e+40
96.9
2.622e+39
3.1
8.514e+40
100.0
26
Au
1110
1110
1110
1110
27
Eu
1442
1442
1442
1442
28
Eu
1442
1461
1461
1442
29
Eg
1461
1461
1461
1461
2.094e+39
2.5
1.689e+39
2.0
3.783e+39
4.4
30
Eg
1461
1592
1592
1461
2.094e+39
2.5
3.182e+39
3.7
5.276e+39
6.2
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.