- BUTSCHLIITE - K₂Ca(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:	166		R-3m
Lattice parameters (Å):	5.3870	5.3870		18.1600
Angles (°):	90	90		120

Symmetry (theoretical):

Space group:	166		R-3m
Lattice parameters (Å):	6.5844	6.5844		6.5844
Angles (°):	46.23	46.23		46.23

Cell contents:

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

Atomic positions (theoretical):

K:	0.2012	0.2012	0.2012
Ca:	0.0000	0.0000	0.0000
C:	0.5803	0.5803	0.5803
O:	0.7221	0.2945	0.7221
O:	0.2945	0.7221	0.7221
O:	0.7221	0.7221	0.2945
K:	0.7988	0.7988	0.7988
C:	0.4197	0.4197	0.4197
O:	0.2779	0.7055	0.2779
O:	0.7055	0.2779	0.2779
O:	0.2779	0.2779	0.7055

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:

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	87	87	87	87
5	Eg	106	106	106	106	1.003e+40 20.4	1.675e+40 34.1	2.678e+40 54.4
6	Eg	106	106	106	106	1.003e+40 20.4	1.171e+40 23.8	2.174e+40 44.2
7	A1u	122	122	122	122
8	A1g	143	143	143	143	4.961e+38 1.0	1.045e+37 0.0	5.065e+38 1.0
9	Eu	159	159	159	159
10	Eu	159	160	160	159
11	Eg	161	161	161	161	9.794e+38 2.0	1.157e+39 2.4	2.136e+39 4.3
12	Eg	161	161	161	161	9.794e+38 2.0	1.636e+39 3.3	2.615e+39 5.3
13	A2u	184	184	184	196
14	Eu	196	196	196	196
15	Eu	196	223	223	216
16	Eg	265	265	265	265	1.262e+40 25.7	1.637e+40 33.3	2.899e+40 59.0
17	Eg	265	265	265	265	1.262e+40 25.7	1.965e+40 40.0	3.227e+40 65.6
18	A1g	289	289	289	289	7.934e+39 16.1	9.926e+38 2.0	8.926e+39 18.2
19	Eu	341	341	341	341
20	Eu	341	361	361	341
21	A2u	361	402	402	414
22	Eg	690	690	690	690	1.285e+39 2.6	1.523e+39 3.1	2.809e+39 5.7
23	Eg	690	690	690	690	1.285e+39 2.6	1.563e+39 3.2	2.849e+39 5.8
24	Eu	695	695	695	695
25	Eu	695	695	695	695
26	A2u	844	844	844	861
27	A1g	876	876	876	876	3.487e+38 0.7	2.601e+38 0.5	6.087e+38 1.2
28	A2u	1120	1120	1120	1122
29	A1g	1122	1122	1122	1122	4.772e+40 97.0	1.452e+39 3.0	4.917e+40 100.0
30	Eg	1434	1434	1434	1434	5.872e+39 11.9	8.308e+39 16.9	1.418e+40 28.8
31	Eg	1434	1434	1434	1434	5.872e+39 11.9	7.804e+39 15.9	1.368e+40 27.8
32	Eu	1463	1463	1463	1463
33	Eu	1463	1589	1589	1463

No.

Char.

ω TO

ω LOx

ω LOy

ω LOz

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I ⊥