-    FERRUCCITE     -    NaBF4

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:  63  Cmcm 
Lattice parameters (Å):  6.8368  6.2619  6.7916 
Angles (°):  90.0  90.0  90.0 

Symmetry (theoretical): 

Space group:  63  Cmcm 
Lattice parameters (Å):  4.4044  4.4044  6.5770 
Angles (°):  90.0  90.0  96.4 

Cell contents: 

Number of atoms:  12 
Number of atom types:  3 
Chemical composition:  0 

Atomic positions (theoretical):

Na:  0.6437  0.6437  0.2500 
B:  0.1468  0.1468  0.2500 
F:  0.2864  0.2864  0.0789 
F:  0.1802  0.8367  0.2500 
Na:  0.3563  0.3563  0.7500 
B:  0.8532  0.8532  0.7500 
F:  0.7136  0.7136  0.5789 
F:  0.8198  0.1633  0.7500 
F:  0.2864  0.2864  0.4211 
F:  0.8367  0.1802  0.2500 
F:  0.7136  0.7136  0.9211 
F:  0.1633  0.8198  0.7500 
Atom type  X  Y  Z 

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: 

Size:

 Nx:  Ny:  Nz: 
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
B1g
38
38
38
38
2.826e+37
0.1
3.885e+37
0.2
6.711e+37
0.3
5
B1g
95
95
95
95
6
A1g
96
96
96
96
1.546e+38
0.7
3.399e+37
0.1
1.886e+38
0.8
7
B3g
108
108
108
108
5.498e+37
0.2
7.559e+37
0.3
1.306e+38
0.6
8
Au
109
109
109
109
9
B2g
113
113
113
113
10
B3g
116
116
116
116
9.385e+36
0.0
1.290e+37
0.1
2.229e+37
0.1
11
B3u
117
129
117
117
12
B1u
132
132
132
136
13
B2u
190
190
190
190
1.492e+36
0.0
2.051e+36
0.0
3.543e+36
0.0
14
B1g
190
190
190
190
1.071e+37
0.0
1.473e+37
0.1
2.544e+37
0.1
15
B3u
190
191
191
190
16
A1g
191
234
234
191
6.746e+37
0.3
2.928e+36
0.0
7.039e+37
0.3
17
B1u
234
238
242
242
18
B3g
242
242
258
272
1.644e+38
0.7
2.260e+38
1.0
3.903e+38
1.7
19
B2g
327
327
327
327
1.314e+39
5.7
1.807e+39
7.8
3.122e+39
13.5
20
Au
332
332
332
332
21
A1g
363
363
363
363
7.977e+38
3.4
5.978e+38
2.6
1.396e+39
6.0
22
B2u
372
372
372
372
23
B1u
500
500
500
502
24
B3u
513
516
513
513
25
B1g
516
516
516
516
1.264e+39
5.5
1.738e+39
7.5
3.002e+39
13.0
26
B3g
520
520
520
520
1.029e+39
4.4
1.415e+39
6.1
2.444e+39
10.5
27
B2u
545
545
548
545
28
A1g
548
548
548
548
7.918e+38
3.4
5.777e+38
2.5
1.369e+39
5.9
29
B2u
775
775
775
775
30
A1g
779
779
779
779
2.317e+40
99.9
1.715e+37
0.1
2.318e+40
100.0
31
B1u
1023
1023
1023
1038
32
B1g
1038
1038
1038
1054
8.071e+38
3.5
1.110e+39
4.8
1.917e+39
8.3
33
A1g
1054
1054
1054
1056
2.947e+38
1.3
2.210e+38
1.0
5.156e+38
2.2
34
B3u
1056
1076
1056
1076
35
B2u
1076
1114
1114
1114
36
B3g
1114
1169
1189
1144
5.270e+38
2.3
7.246e+38
3.1
1.252e+39
5.4
No.  Char.  ω TO  ω LOx  ω LOy  ω LOz  I ∥  I ⊥  I Total 

You can define the size of the supercell for the visualization of the vibration.

Nx: 
Ny: 
Nz: 
Normalized
Raw
Options for intensity.
 

Single Crystal Raman spectra

Single crystal 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.

The Raman measurements performed on single crystals employ polarized lasers and allow for the selection of specific elements of the individual Raman tensors of the Raman-active modes.

By convention, in the following we assume a measurement as X(XZ)Z, i.e. incident laser polarized along the X axis, emergent light polarized along the Z axis. If the crystal is aligned with the xyz reference frame, we sample the αxz element. As you rotate the crystal you can sample other entries of the Raman tensor or various linear combineations.

Horizontal:
Xmin:
Xmax:
Vertical:
Ymin:
Ymax:
 


Choose the orientation of the crystal with respect to the reference system:

 
Rotation around X axis:
Rotation around Z axis:
Rotation around Y axis: