-    CALCITE     -    CaCO3

Theoretical atomic positions 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:  167  R-3c 
Lattice parameters (Å):  2.5930  2.5930  8.9431 
Angles (°):  90.0  90.0  120.0 

Symmetry (theoretical): 

Space group:  167  R-3c 
Lattice parameters (Å):  6.3310  6.3310  6.3310 
Angles (°):  46.7  46.7  46.7 

Cell contents: 

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

Atomic positions (theoretical):

Ca:  0.0000  0.0000  0.0000 
C:  0.2500  0.2500  0.2500 
O:  0.5050  0.9950  0.2500 
O:  0.9950  0.2500  0.5050 
Ca:  0.5000  0.5000  0.5000 
C:  0.7500  0.7500  0.7500 
O:  0.7500  0.4950  0.0050 
O:  0.2500  0.5050  0.9950 
O:  0.4950  0.0050  0.7500 
O:  0.0050  0.7500  0.4950 
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
A2u
93
93
93
108
5
Eu
108
108
108
108
6
Eu
108
128
128
141
7
Eg
159
159
159
159
5.071e+39
7.7
7.089e+39
10.8
1.216e+40
18.6
8
Eg
159
159
159
159
5.071e+39
7.7
7.496e+39
11.4
1.257e+40
19.2
9
A2g
161
161
161
161
10
Eu
244
244
244
244
11
Eu
244
260
260
244
12
Eg
297
297
297
297
1.249e+40
19.1
1.088e+40
16.6
2.337e+40
35.7
13
Eg
297
297
297
297
1.249e+40
19.1
2.035e+40
31.1
3.284e+40
50.2
14
A1u
299
299
299
299
15
A2g
329
329
329
329
16
Eu
333
333
333
333
17
Eu
333
350
350
333
18
A2u
350
404
404
427
19
Eg
705
705
705
705
2.033e+39
3.1
2.281e+39
3.5
4.314e+39
6.6
20
Eg
705
705
705
705
2.034e+39
3.1
1.806e+39
2.8
3.839e+39
5.9
21
Eu
708
708
708
708
22
Eu
708
710
710
708
23
A2u
849
849
849
854
24
A2g
854
854
854
865
25
A1g
1092
1092
1092
1092
8.496e+38
1.3
2.691e+37
0.0
8.765e+38
1.3
26
A1u
1092
1092
1092
1092
6.346e+40
96.9
2.010e+39
3.1
6.548e+40
100.0
27
Eu
1413
1413
1413
1413
28
Eu
1413
1440
1440
1413
29
Eg
1440
1440
1440
1440
2.122e+39
3.2
2.347e+39
3.6
4.469e+39
6.8
30
Eg
1440
1555
1555
1440
2.122e+39
3.2
1.888e+39
2.9
4.009e+39
6.1
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.