- ROMARKITE - SnO

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):	3.7986	3.7986		4.8408
Angles (°):	90.0	90.0		90.0

Symmetry (theoretical):

Space group:	129		P4/nmm
Lattice parameters (Å):	3.7986	3.7986		4.8408
Angles (°):	90.0	90.0		90.0

Cell contents:

Number of atoms:	4
Number of atom types:	2
Chemical composition:	0

Atomic positions (theoretical):

Sn:	0.0000	0.0000	0.2369
Sn:	0.0000	0.0000	0.7631
O:	0.0000	0.0000	0.0000
O:	0.0000	0.0000	0.0000

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	E1g	122	122	122	122	4.652e+41 14.9	6.396e+41 20.5	1.105e+42 35.4
5	E1g	122	122	122	122	4.652e+41 14.9	6.396e+41 20.5	1.105e+42 35.4
6	A1g	214	214	214	214	3.067e+42 98.3	5.433e+40 1.7	3.121e+42 100.0
7	E1u	307	307	307	307
8	E1u	307	374	374	307
9	B1g	374	402	402	374	9.436e+40 3.0	7.077e+40 2.3	1.651e+41 5.3
10	A2u	402	467	467	479
11	E1g	479	479	479	479	1.296e+40 0.4	1.782e+40 0.6	3.078e+40 1.0
12	E1g	479	479	479	526	1.296e+40 0.4	1.782e+40 0.6	3.078e+40 1.0

No.

Char.

ω TO

ω LOx

ω LOy

ω LOz

I ∥

I ⊥