-    BRUCITE     -    Mg(OH)2

Theoretical atomic positions and lattice parameters at experimental volum from 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:  164  P-3m1 
Lattice parameters (Å):  3.1498  3.1498  4.7702 
Angles (°):  90.0  90.0  120.0 

Symmetry (theoretical): 

Space group:  164  P-3m1 
Lattice parameters (Å):  3.1445  3.1445  4.7862 
Angles (°):  90.0  90.0  120.0 

Cell contents: 

Number of atoms: 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

Mg:  0.0000  0.0000  0.0000 
O:  0.3333  0.6667  0.2143 
H:  0.3333  0.6667  0.4169 
O:  0.6667  0.3333  0.7857 
H:  0.6667  0.3333  0.5831 
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: 

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.

Horizontal:
Xmin:
Xmax:
Vertical:
Ymin:
Ymax:
 
Choose the polarization of the lasers.
I ∥ 
I ⊥ 
I Total 

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
266
266
266
266
1.010e+40
2.5
1.059e+40
2.6
2.069e+40
5.2
5
Eg
266
266
266
266
1.010e+40
2.5
1.686e+40
4.2
2.696e+40
6.7
6
Eu
354
354
354
354
7
Eu
354
373
373
354
8
Eu
412
412
412
412
9
Eu
412
428
428
412
10
A1g
428
480
480
428
1.428e+40
3.6
9.118e+38
0.2
1.519e+40
3.8
11
A2u
480
730
729
594
12
Eg
782
782
782
782
1.309e+40
3.3
1.317e+40
3.3
2.626e+40
6.6
13
Eg
782
782
782
782
1.309e+40
3.3
2.204e+40
5.5
3.514e+40
8.8
14
A1g
3590
3590
3590
3590
3.661e+41
91.5
3.415e+40
8.5
4.002e+41
100.0
15
A2u
3639
3639
3639
3658
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.