-    ANHYDRITE     -    CaSO4

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:  P-1 
Lattice parameters (Å):  6.9930  6.9950  6.2450 
Angles (°):  90  90  90 

Symmetry (theoretical): 

Space group:  P-1 
Lattice parameters (Å):  5.3755  5.3755  5.5136 
Angles (°):       

Cell contents: 

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

Atomic positions (theoretical):

Ca:  0.7500  0.2500  0.3944 
S:  0.2500  0.7500  0.0916 
O:  0.3849  0.8849  0.9421 
O:  0.0727  0.9273  0.2624 
Ca:  0.2500  0.7500  0.6056 
S:  0.7500  0.2500  0.9084 
O:  0.6151  0.1151  0.0579 
O:  0.5727  0.4273  0.7376 
O:  0.1151  0.6151  0.9421 
O:  0.4273  0.5727  0.2624 
O:  0.8849  0.3849  0.0579 
O:  0.9273  0.0727  0.7376 
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
Au
-176
-176
-176
-176
2
Ag
-169
-169
-169
-169
3
Au
-106
-106
-61
-106
4
Ag
-61
-61
-50
-61
5
Ag
-50
-50
-8
-50
6
ac
0
0
0
0
7
ac
0
0
0
0
8
ac
0
0
0
0
9
Ag
148
148
148
148
2.779e+40
21.9
1.919e+39
1.5
2.970e+40
23.4
10
Ag
154
154
154
154
6.937e+38
0.5
9.539e+38
0.8
1.648e+39
1.3
11
Au
273
304
273
273
12
Ag
307
307
307
307
5.173e+39
4.1
7.113e+39
5.6
1.229e+40
9.7
13
Ag
347
347
347
347
5.060e+38
0.4
6.957e+38
0.5
1.202e+39
0.9
14
Au
384
384
384
384
15
Au
412
412
412
412
16
Ag
439
439
439
439
4.178e+38
0.3
5.744e+38
0.5
9.922e+38
0.8
17
Ag
522
522
522
522
3.861e+39
3.0
2.598e+39
2.0
6.459e+39
5.1
18
Au
525
526
525
525
19
Ag
526
526
526
526
1.104e+39
0.9
1.518e+39
1.2
2.622e+39
2.1
20
Au
557
557
557
574
21
Au
574
601
574
600
22
Au
608
608
626
608
23
Ag
646
646
646
646
1.879e+37
0.0
2.584e+37
0.0
4.462e+37
0.0
24
Au
648
648
648
648
25
Ag
660
660
660
660
2.790e+40
22.0
6.768e+39
5.3
3.467e+40
27.3
26
Ag
662
662
662
662
2.188e+39
1.7
3.008e+39
2.4
5.196e+39
4.1
27
Au
704
704
704
755
28
Ag
784
784
784
784
3.408e+40
26.9
1.760e+40
13.9
5.169e+40
40.8
29
Au
1061
1067
1061
1061
30
Au
1067
1089
1067
1073
31
Ag
1089
1126
1089
1089
1.232e+41
97.2
3.595e+39
2.8
1.268e+41
100.0
32
Ag
1126
1193
1126
1126
5.433e+39
4.3
7.471e+39
5.9
1.290e+40
10.2
33
Au
1274
1274
1274
1277
34
Ag
1277
1277
1277
1283
8.254e+40
65.1
1.763e+40
13.9
1.002e+41
79.0
35
Au
1283
1283
1337
1342
36
Ag
1342
1342
1342
1356
1.512e+39
1.2
2.079e+39
1.6
3.591e+39
2.8
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.