-    POTASSIUM CARBONATE     -    K2CO3

Theoretical atomic positions and lattice parameters at experimental volum 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:  12  C2/m 
Lattice parameters (Å):  8.9050  5.2370  6.0450 
Angles (°):  90  101.32  90 

Symmetry (theoretical): 

Space group:  12  C2/m 
Lattice parameters (Å):  5.1544  5.1544  6.0636 
Angles (°):  75.99  104.00  116.96 

Cell contents: 

Number of atoms:  12 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

K:  0.0000  0.0000  0.0000 
K:  0.0000  0.0000  0.5000 
K:  0.6661  0.3339  0.7219 
H:  0.6628  0.3372  0.2504 
O:  0.4060  0.1905  0.3038 
O:  0.7730  0.2270  0.1518 
K:  0.3339  0.6661  0.2781 
H:  0.3372  0.6628  0.7496 
O:  0.1905  0.4060  0.6962 
O:  0.2270  0.7730  0.8482 
O:  0.5940  0.8095  0.6962 
O:  0.8095  0.5940  0.3038 
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
69
69
87
69
5
Au
87
87
103
87
6
Bg
103
103
104
103
6.303e+38
1.0
7.175e+38
1.1
1.348e+39
2.1
7
Bu
144
144
144
148
8
Ag
151
151
151
151
3.788e+38
0.6
2.102e+38
0.3
5.889e+38
0.9
9
Ag
171
171
171
171
5.661e+38
0.9
6.282e+38
1.0
1.194e+39
1.9
10
Bg
174
174
174
174
8.500e+38
1.3
1.014e+39
1.6
1.864e+39
2.9
11
Bu
192
192
192
198
12
Bu
206
207
206
206
13
Au
212
212
216
212
14
Bg
246
246
246
246
2.672e+39
4.2
2.960e+39
4.7
5.633e+39
8.9
15
Bu
254
262
254
254
16
Ag
273
273
273
273
2.756e+38
0.4
1.347e+38
0.2
4.103e+38
0.6
17
Bg
277
277
277
277
4.738e+39
7.5
4.929e+39
7.8
9.667e+39
15.2
18
Bg
277
277
277
277
3.389e+39
5.3
3.702e+39
5.8
7.091e+39
11.2
19
Bu
292
299
292
297
20
Au
299
310
306
299
21
Ag
318
318
318
318
3.570e+39
5.6
3.218e+39
5.1
6.788e+39
10.7
22
Au
332
332
341
332
23
Bu
341
345
346
345
24
Bu
346
373
364
387
25
Bg
703
703
703
703
2.211e+39
3.5
3.711e+39
5.8
5.922e+39
9.3
26
Au
708
708
708
708
27
Ag
728
728
728
728
1.993e+39
3.1
1.637e+39
2.6
3.630e+39
5.7
28
Bu
729
730
729
730
29
Bu
868
869
868
876
30
Ag
876
876
876
876
5.233e+38
0.8
3.644e+38
0.6
8.877e+38
1.4
31
Ag
1130
1130
1130
1130
6.028e+40
95.0
3.178e+39
5.0
6.345e+40
100.0
32
Bu
1132
1132
1132
1132
33
Au
1477
1477
1484
1477
34
Bg
1484
1484
1485
1484
1.890e+39
3.0
3.185e+39
5.0
5.074e+39
8.0
35
Bu
1485
1508
1508
1508
36
Ag
1508
1576
1587
1520
1.344e+39
2.1
1.290e+39
2.0
2.634e+39
4.2
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.