- MOLYBDOMENITE - PbSeO₃

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. Tetter norm-conserving pseudopotential for Pb.

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:	11		P2_1/m
Lattice parameters (Å):	4.5437	5.5137		6.6340
Angles (°):	90	106.547		90

Symmetry (theoretical):

Space group:	11		P2_1/m
Lattice parameters (Å):	4.4224	5.4651		6.4548
Angles (°):	90	90		90

Cell contents:

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

Atomic positions (theoretical):

Pb:	0.6409	0.2500	0.3019
Se:	0.0885	0.7500	0.1543
O:	0.6922	0.7500	0.1134
O:	0.2011	0.5116	0.3320
Pb:	0.3591	0.7500	0.6981
Se:	0.9115	0.2500	0.8457
O:	0.3078	0.2500	0.8866
O:	0.7989	0.0116	0.6680
O:	0.7989	0.4884	0.6680
O:	0.2011	0.9884	0.3320

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	Bg	53	53	53	53	3.508e+40 2.2	5.507e+40 3.5	9.015e+40 5.7
5	Ag	59	59	59	59	3.284e+40 2.1	1.872e+40 1.2	5.156e+40 3.3
6	Au	62	62	71	62
7	Ag	71	71	75	71	7.635e+40 4.8	3.129e+40 2.0	1.076e+41 6.8
8	Bg	75	75	77	75	4.026e+40 2.5	4.684e+40 3.0	8.710e+40 5.5
9	Ag	77	77	90	77	2.425e+40 1.5	1.013e+40 0.6	3.438e+40 2.2
10	Bu	90	90	97	97
11	Bu	97	119	98	119
12	Ag	119	121	119	121	1.491e+41 9.4	4.856e+39 0.3	1.539e+41 9.7
13	Au	121	141	136	141
14	Bg	141	143	141	153	2.321e+39 0.1	3.601e+39 0.2	5.922e+39 0.4
15	Au	153	153	193	169
16	Ag	193	193	204	193	2.845e+40 1.8	2.573e+40 1.6	5.418e+40 3.4
17	Bg	204	204	211	204	4.978e+40 3.1	5.761e+40 3.6	1.074e+41 6.8
18	Bu	211	242	222	219
19	Ag	341	341	341	341	1.157e+41 7.3	6.974e+40 4.4	1.854e+41 11.7
20	Au	345	345	351	345
21	Bg	354	354	354	354	1.001e+41 6.3	1.532e+41 9.7	2.534e+41 16.0
22	Bu	367	380	367	372
23	Bu	416	423	416	423
24	Ag	423	432	423	463	2.884e+40 1.8	1.665e+40 1.1	4.549e+40 2.9
25	Au	648	648	673	648
26	Bg	673	673	691	673	1.052e+40 0.7	1.261e+40 0.8	2.313e+40 1.5
27	Bu	691	698	698	698
28	Ag	698	751	737	717	2.798e+41 17.6	1.074e+41 6.8	3.873e+41 24.4
29	Bu	762	772	762	772
30	Ag	772	777	772	776	1.505e+42 94.9	8.104e+40 5.1	1.586e+42 100.0

No.

Char.

ω TO

ω LOx

ω LOy

ω LOz

I ∥

I ⊥