- OTAVITE - CdCO₃

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:	167		R-3c
Lattice parameters (Å):	4.9207	4.9207		16.2968
Angles (°):	90.0	90.0		120.0

Symmetry (theoretical):

Space group:	167		R-3c
Lattice parameters (Å):	6.0189	6.0189		6.0189
Angles (°):	48.4	48.4		48.4

Cell contents:

Number of atoms:	10
Number of atom types:	3
Chemical composition:	0

Atomic positions (theoretical):

Cd:	0.0000	0.0000	0.0000
C:	0.2500	0.2500	0.2500
O:	0.5086	0.9914	0.2500
O:	0.9914	0.2500	0.5086
Cd:	0.5000	0.5000	0.5000
C:	0.7500	0.7500	0.7500
O:	0.7500	0.4914	0.0086
O:	0.2500	0.5086	0.9914
O:	0.4914	0.0086	0.7500
O:	0.0086	0.7500	0.4914

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	A2u	77	77	77	107
5	Eu	107	107	107	107
6	Eu	107	116	116	145
7	Eu	159	159	159	159
8	Eu	159	165	165	159
9	Eg	165	165	165	165	1.000e+40 9.9	1.312e+40 13.0	2.312e+40 22.9
10	Eg	165	169	169	165	1.000e+40 9.9	1.505e+40 14.9	2.505e+40 24.8
11	A1u	169	186	186	169
12	A2g	193	193	193	193
13	Eg	272	272	272	272	4.000e+40 39.6	6.106e+40 60.4	1.011e+41 100.0
14	Eg	272	272	272	272	4.000e+40 39.6	3.174e+40 31.4	7.175e+40 71.0
15	Eu	292	292	292	292
16	Eu	292	328	328	292
17	A2u	328	338	338	371
18	A2g	384	384	384	384
19	Eg	706	706	706	706	3.678e+38 0.4	5.048e+38 0.5	8.726e+38 0.9
20	Eg	706	706	706	706	3.678e+38 0.4	5.198e+38 0.5	8.875e+38 0.9
21	Eu	714	714	714	714
22	Eu	714	715	715	714
23	A2u	830	830	830	836
24	A2g	836	836	836	840
25	A1u	1094	1094	1094	1094
26	A1g	1096	1096	1096	1096	9.524e+40 94.2	2.102e+39 2.1	9.734e+40 96.3
27	Eu	1397	1397	1397	1397
28	Eu	1397	1400	1400	1397
29	Eg	1400	1400	1400	1400	3.361e+40 33.3	5.555e+40 55.0	8.916e+40 88.2
30	Eg	1400	1541	1541	1400	3.361e+40 33.3	3.080e+40 30.5	6.441e+40 63.7

No.

Char.

ω TO

ω LOx

ω LOy

ω LOz

I ∥

I ⊥