- MATLOCKITE - PbFCl

Theoretical atomic positions. Lattice parameters fixed as 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:	129		P4/nmm
Lattice parameters (Å):	4.1060	4.1060		7.2300
Angles (°):	90.0	90.0		90.0

Symmetry (theoretical):

Space group:	129		P4/nmm
Lattice parameters (Å):	4.1060	4.1060		7.2300
Angles (°):	90.0	90.0		90.0

Cell contents:

Number of atoms:	6
Number of atom types:	3
Chemical composition:	0

Atomic positions (theoretical):

Pb:	0.0000	0.5000	0.2029
F:	0.0000	0.0000	0.0000
Cl:	0.0000	0.5000	0.6520
F:	0.5000	0.5000	0.0000
Pb:	0.5000	0.0000	0.7971
Cl:	0.5000	0.0000	0.3480

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	Eg	32	32	32	32	1.183e+40 4.5	1.626e+40 6.2	2.809e+40 10.7
5	Eg	32	32	32	32	1.183e+40 4.5	1.627e+40 6.2	2.810e+40 10.7
6	Eu	41	41	41	41
7	Eu	41	67	67	41
8	A2u	67	96	96	96
9	A1g	96	112	112	112	9.752e+40 37.3	3.043e+40 11.6	1.280e+41 48.9
10	Eg	112	112	112	112	5.214e+40 19.9	7.169e+40 27.4	1.238e+41 47.4
11	Eg	112	137	137	145	5.214e+40 19.9	7.169e+40 27.4	1.238e+41 47.4
12	A1g	145	145	145	158	1.512e+41 57.8	1.102e+41 42.2	2.614e+41 100.0
13	Eu	158	158	158	158
14	Eu	158	213	213	162
15	B1g	213	228	228	213	3.653e+40 14.0	2.740e+40 10.5	6.393e+40 24.5
16	Eg	228	228	228	228	3.414e+40 13.1	4.695e+40 18.0	8.109e+40 31.0
17	Eg	228	253	253	228	3.414e+40 13.1	4.695e+40 18.0	8.109e+40 31.0
18	A2u	276	276	276	333

No.

Char.

ω TO

ω LOx

ω LOy

ω LOz

I ∥

I ⊥