-    EITELITE     -    Na2Mg(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):  4.9460  4.9460  16.4220 
Angles (°):  90.0  90.0  120.0 

Symmetry (theoretical): 

Space group:  148  R-3 
Lattice parameters (Å):  5.9484  5.9484  5.9484 
Angles (°):  48.0  48.0  48.0 

Cell contents: 

Number of atoms:  11 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

Na:  0.1960  0.1960  0.1960 
Mg:  0.0000  0.0000  0.0000 
C:  0.5899  0.5899  0.5899 
O:  0.8107  0.2969  0.6579 
O:  0.2969  0.6579  0.8107 
O:  0.6579  0.8107  0.2969 
Na:  0.8040  0.8040  0.8040 
C:  0.4101  0.4101  0.4101 
O:  0.1893  0.7031  0.3421 
O:  0.7031  0.3421  0.1893 
O:  0.3421  0.1893  0.7031 
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
Eg
117
117
117
117
1.066e+40
13.2
1.634e+40
20.3
2.700e+40
33.5
5
Eg
117
117
117
117
1.066e+40
13.2
1.521e+40
18.9
2.587e+40
32.1
6
Ag
142
142
142
142
7.172e+38
0.9
1.823e+38
0.2
8.995e+38
1.1
7
Au
153
153
153
204
8
Eu
204
204
204
204
9
Eu
204
217
217
213
10
Ag
217
218
218
217
6.180e+38
0.8
2.190e+36
0.0
6.202e+38
0.8
11
Eg
225
225
225
225
3.665e+39
4.5
4.668e+39
5.8
8.333e+39
10.3
12
Eg
225
225
225
225
3.665e+39
4.5
5.115e+39
6.4
8.779e+39
10.9
13
Eu
257
257
257
257
14
Eu
257
271
271
257
15
Au
278
278
278
291
16
Eg
291
291
291
291
3.008e+39
3.7
4.468e+39
5.5
7.476e+39
9.3
17
Eg
291
291
291
296
3.008e+39
3.7
3.595e+39
4.5
6.603e+39
8.2
18
Ag
333
333
333
333
1.863e+39
2.3
2.011e+38
0.2
2.064e+39
2.6
19
Eu
373
373
373
373
20
Eu
373
408
408
373
21
Au
408
462
462
455
22
Eg
709
709
709
709
1.410e+39
1.8
1.117e+39
1.4
2.527e+39
3.1
23
Eg
709
709
709
709
1.410e+39
1.8
1.795e+39
2.2
3.205e+39
4.0
24
Eu
714
714
714
714
25
Eu
714
714
714
714
26
Au
848
848
848
873
27
Ag
881
881
881
881
6.429e+38
0.8
2.620e+38
0.3
9.049e+38
1.1
28
Au
1111
1111
1111
1112
29
Ag
1113
1113
1113
1113
7.796e+40
96.8
2.581e+39
3.2
8.054e+40
100.0
30
Eg
1426
1426
1426
1426
1.740e+39
2.2
2.079e+39
2.6
3.819e+39
4.7
31
Eg
1426
1426
1426
1426
1.740e+39
2.2
1.395e+39
1.7
3.135e+39
3.9
32
Eu
1458
1458
1458
1458
33
Eu
1458
1598
1598
1458
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.