-    DOLOMITE     -    CaMg(CO3)2

Theoretical atomic position and lattice parameters at experimental volume 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:  148  R-3 
Lattice parameters (Å):  4.8079  4.8079  16.0100 
Angles (°):  90.0  90.0  120.0 

Symmetry (theoretical): 

Space group:  148  R-3 
Lattice parameters (Å):  6.0075  6.0075  6.0075 
Angles (°):  47.2  47.2  47.2 

Cell contents: 

Number of atoms:  10 
Number of atom types:  4 
Chemical composition:  0 

Atomic positions (theoretical):

Ca:  0.0000  0.0000  0.0000 
Mg:  0.5000  0.5000  0.5000 
C:  0.2417  0.2417  0.2417 
O:  0.4874  0.9599  0.2811 
O:  0.9599  0.2811  0.4874 
O:  0.2811  0.4874  0.9599 
C:  0.7583  0.7583  0.7583 
O:  0.5126  0.0401  0.7189 
O:  0.0401  0.7189  0.5126 
O:  0.7189  0.5126  0.0401 
Atom type  X  Y  Z 

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
ac
0
0
0
0
2
ac
0
0
0
0
3
ac
0
0
0
0
4
Au
153
153
153
154
5
Eu
154
154
154
154
6
Eu
154
172
172
172
7
Eg
172
172
172
172
5.915e+39
7.4
6.002e+39
7.5
1.192e+40
14.9
8
Eg
172
175
175
196
5.915e+39
7.4
7.748e+39
9.7
1.366e+40
17.1
9
Ag
213
213
213
213
2.446e+38
0.3
1.547e+38
0.2
3.993e+38
0.5
10
Eu
264
264
264
264
11
Eu
264
273
273
264
12
Eg
297
297
297
297
9.924e+39
12.4
1.657e+40
20.7
2.649e+40
33.2
13
Eg
297
297
297
297
9.924e+39
12.4
1.021e+40
12.8
2.013e+40
25.2
14
Au
320
320
320
328
15
Ag
334
334
334
334
5.466e+37
0.1
2.653e+37
0.0
8.119e+37
0.1
16
Eu
347
347
347
347
17
Eu
347
358
358
347
18
Au
358
441
441
437
19
Eg
711
711
711
711
2.290e+39
2.9
1.986e+39
2.5
4.276e+39
5.4
20
Eg
711
711
711
711
2.290e+39
2.9
2.708e+39
3.4
4.998e+39
6.3
21
Eu
715
715
715
715
22
Eu
715
717
717
715
23
Au
851
851
851
859
24
Ag
859
859
859
872
2.636e+38
0.3
1.246e+36
0.0
2.648e+38
0.3
25
Ag
1092
1092
1092
1092
2.148e+39
2.7
6.911e+37
0.1
2.218e+39
2.8
26
Au
1093
1093
1093
1093
7.741e+40
96.9
2.490e+39
3.1
7.990e+40
100.0
27
Eu
1420
1420
1420
1420
28
Eu
1420
1438
1438
1420
29
Eg
1438
1438
1438
1438
2.206e+39
2.8
2.236e+39
2.8
4.442e+39
5.6
30
Eg
1438
1568
1568
1438
2.206e+39
2.8
2.911e+39
3.6
5.117e+39
6.4
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.