-    BUTSCHLIITE     -    K2Ca(CO3)2

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:  166  R-3m 
Lattice parameters (Å):  5.3870  5.3870  18.1600 
Angles (°):  90.0  90.0  120.0 

Symmetry (theoretical): 

Space group:  166  R-3m 
Lattice parameters (Å):  6.9600  6.9600  6.9600 
Angles (°):  44.8  44.8  44.8 

Cell contents: 

Number of atoms:  11 
Number of atom types:  4 
Chemical composition:  0 

Atomic positions (theoretical):

K:  0.1992  0.1992  0.1992 
Ca:  0.0000  0.0000  0.0000 
C:  0.5828  0.5828  0.5828 
O:  0.7221  0.3023  0.7221 
O:  0.3023  0.7221  0.7221 
O:  0.7221  0.7221  0.3023 
K:  0.8008  0.8008  0.8008 
C:  0.4172  0.4172  0.4172 
O:  0.2779  0.6977  0.2779 
O:  0.6977  0.2779  0.2779 
O:  0.2779  0.2779  0.6977 
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
A2g
59
59
59
59
5
Eg
77
77
77
77
1.336e+40
30.2
1.881e+40
42.5
3.218e+40
72.7
6
Eg
77
77
77
77
1.336e+40
30.2
1.915e+40
43.3
3.251e+40
73.5
7
A1u
87
87
87
87
8
A1g
92
92
92
92
2.606e+37
0.1
1.728e+37
0.0
4.334e+37
0.1
9
Eu
107
107
107
107
10
Eu
107
122
122
107
11
Eg
122
122
122
122
2.494e+38
0.6
2.900e+38
0.7
5.394e+38
1.2
12
Eg
122
128
128
122
2.494e+38
0.6
4.178e+38
0.9
6.672e+38
1.5
13
A2u
129
129
129
175
14
Eu
175
175
175
175
15
Eu
175
186
186
179
16
Eg
206
206
206
206
1.796e+40
40.6
2.508e+40
56.7
4.304e+40
97.2
17
Eg
206
206
206
206
1.796e+40
40.6
2.630e+40
59.4
4.426e+40
100.0
18
A1g
231
231
231
231
6.360e+39
14.4
8.016e+38
1.8
7.162e+39
16.2
19
Eu
265
265
265
265
20
Eu
265
293
293
265
21
A2u
293
340
340
351
22
Eg
672
672
672
672
6.060e+38
1.4
6.269e+38
1.4
1.233e+39
2.8
23
Eg
672
672
672
672
6.060e+38
1.4
8.923e+38
2.0
1.498e+39
3.4
24
Eu
672
672
672
672
25
Eu
672
672
672
672
26
A2u
851
851
851
862
27
A1g
871
871
871
871
2.236e+38
0.5
1.671e+38
0.4
3.907e+38
0.9
28
A2u
1078
1078
1078
1078
29
A1g
1080
1080
1080
1080
4.277e+40
96.6
1.428e+39
3.2
4.419e+40
99.9
30
Eg
1384
1384
1384
1384
6.644e+39
15.0
9.935e+39
22.4
1.658e+40
37.5
31
Eg
1384
1384
1384
1384
6.644e+39
15.0
7.903e+39
17.9
1.455e+40
32.9
32
Eu
1409
1409
1409
1409
33
Eu
1409
1532
1532
1409
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.
 

Single Crystal Raman spectra

Single crystal 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.

The Raman measurements performed on single crystals employ polarized lasers and allow for the selection of specific elements of the individual Raman tensors of the Raman-active modes.

By convention, in the following we assume a measurement as X(XZ)Z, i.e. incident laser polarized along the X axis, emergent light polarized along the Z axis. If the crystal is aligned with the xyz reference frame, we sample the αxz element. As you rotate the crystal you can sample other entries of the Raman tensor or various linear combineations.

Horizontal:
Xmin:
Xmax:
Vertical:
Ymin:
Ymax:
 


Choose the orientation of the crystal with respect to the reference system:

 
Rotation around X axis:
Rotation around Z axis:
Rotation around Y axis: