-    CROCOITE     -    PbCrO4

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. Tetter norm-conserving pseudopotential for Cr. 

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:  14  P2_1/n 
Lattice parameters (Å):  7.1200  7.4300  6.7900 
Angles (°):  90  102.42  90 

Symmetry (theoretical): 

Space group:  14  P2_1/n 
Lattice parameters (Å):  7.0193  7.3464  6.7203 
Angles (°):  90  102.70  90 

Cell contents: 

Number of atoms:  24 
Number of atom types:  3 
Chemical composition:  0 

Atomic positions (theoretical):

Pb:  0.2228  0.1448  0.3995 
Cr:  0.2016  0.1659  0.8808 
O:  0.0277  0.0987  0.6799 
O:  0.1217  0.3504  0.9851 
O:  0.2476  0.5064  0.4366 
O:  0.3914  0.2154  0.7782 
Pb:  0.2772  0.6448  0.1005 
Cr:  0.2984  0.6659  0.6192 
O:  0.4723  0.5987  0.8201 
O:  0.3783  0.8504  0.5149 
O:  0.2524  0.0064  0.0634 
O:  0.1086  0.7154  0.7218 
Pb:  0.7772  0.8552  0.6005 
Cr:  0.7984  0.8341  0.1192 
O:  0.9723  0.9013  0.3201 
O:  0.8783  0.6496  0.0149 
O:  0.7524  0.4936  0.5634 
O:  0.6086  0.7846  0.2218 
Pb:  0.7228  0.3552  0.8995 
Cr:  0.7016  0.3341  0.3808 
O:  0.5277  0.4013  0.1799 
O:  0.6217  0.1496  0.4851 
O:  0.7476  0.9936  0.9366 
O:  0.8914  0.2846  0.2782 
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
Bg
43
43
43
43
1.986e+40
0.7
2.115e+40
0.7
4.101e+40
1.4
5
Ag
46
46
46
46
5.848e+40
2.0
3.010e+40
1.0
8.858e+40
3.0
6
Bu
49
49
49
49
7
Ag
52
52
52
52
3.772e+39
0.1
1.820e+39
0.1
5.592e+39
0.2
8
Ag
57
57
57
57
6.314e+40
2.1
4.076e+40
1.4
1.039e+41
3.5
9
Au
59
59
59
59
10
Bg
59
59
59
59
1.266e+38
0.0
1.929e+38
0.0
3.195e+38
0.0
11
Bu
59
60
60
59
1.234e+40
0.4
1.881e+40
0.6
3.115e+40
1.1
12
Bg
65
65
65
65
9.000e+39
0.3
1.089e+40
0.4
1.989e+40
0.7
13
Bg
77
77
77
77
4.672e+39
0.2
7.735e+39
0.3
1.241e+40
0.4
14
Bu
83
83
85
83
15
Au
85
92
93
87
16
Ag
93
93
96
93
2.977e+40
1.0
2.064e+40
0.7
5.041e+40
1.7
17
Au
96
99
99
99
18
Ag
99
101
99
101
1.953e+40
0.7
1.036e+39
0.0
2.057e+40
0.7
19
Bu
101
109
109
108
20
Ag
109
115
111
109
5.836e+40
2.0
4.232e+40
1.4
1.007e+41
3.4
21
Bg
115
117
115
115
1.747e+40
0.6
2.129e+40
0.7
3.876e+40
1.3
22
Bu
117
119
119
117
23
Au
119
122
124
120
24
Au
124
126
126
126
25
Bg
126
138
137
138
1.496e+40
0.5
1.605e+40
0.5
3.101e+40
1.1
26
Bu
138
143
142
143
27
Ag
143
143
143
153
1.858e+41
6.3
4.258e+40
1.4
2.284e+41
7.7
28
Bg
153
153
153
154
5.547e+40
1.9
5.954e+40
2.0
1.150e+41
3.9
29
Bg
157
157
157
157
3.368e+39
0.1
5.556e+39
0.2
8.924e+39
0.3
30
Au
161
162
161
162
31
Bu
162
164
164
164
32
Ag
164
174
178
178
1.288e+40
0.4
1.527e+40
0.5
2.815e+40
1.0
33
Bu
178
178
185
182
34
Au
185
191
188
191
35
Bg
191
195
191
195
1.455e+40
0.5
2.376e+40
0.8
3.832e+40
1.3
36
Ag
195
197
195
200
1.075e+41
3.6
5.899e+40
2.0
1.665e+41
5.6
37
Au
300
300
300
300
38
Bu
304
304
305
304
39
Bg
310
310
310
310
1.702e+41
5.8
1.986e+41
6.7
3.688e+41
12.5
40
Ag
323
323
323
323
4.199e+41
14.2
2.953e+41
10.0
7.152e+41
24.3
41
Bu
325
325
327
325
42
Au
336
337
336
336
43
Ag
339
339
339
339
4.383e+41
14.9
3.491e+41
11.8
7.874e+41
26.7
44
Bg
340
340
340
340
8.585e+40
2.9
1.139e+41
3.9
1.998e+41
6.8
45
Bu
345
345
346
345
46
Ag
346
346
346
346
1.080e+42
36.6
7.193e+41
24.4
1.799e+42
61.0
47
Bu
356
356
356
356
48
Bg
361
361
361
361
1.161e+40
0.4
1.243e+40
0.4
2.404e+40
0.8
49
Ag
365
365
365
365
3.117e+41
10.6
8.946e+40
3.0
4.012e+41
13.6
50
Au
367
369
367
368
51
Au
373
374
373
373
52
Bg
374
378
374
374
4.822e+40
1.6
5.327e+40
1.8
1.015e+41
3.4
53
Au
385
385
385
385
54
Ag
390
390
390
390
1.801e+41
6.1
9.897e+40
3.4
2.791e+41
9.5
55
Bg
390
390
390
390
6.196e+40
2.1
6.925e+40
2.3
1.312e+41
4.5
56
Bu
411
411
411
411
57
Au
897
899
897
903
58
Bu
903
903
903
903
59
Ag
903
903
905
903
2.143e+42
72.7
1.515e+41
5.1
2.294e+42
77.9
60
Bg
905
905
906
905
2.018e+39
0.1
2.669e+39
0.1
4.686e+39
0.2
61
Au
906
907
906
906
62
Ag
907
907
907
907
9.176e+41
31.1
1.784e+40
0.6
9.354e+41
31.7
63
Bu
907
908
909
907
2.891e+42
98.1
5.621e+40
1.9
2.947e+42
100.0
64
Au
909
917
920
920
65
Ag
920
920
923
924
9.178e+41
31.1
6.899e+40
2.3
9.868e+41
33.5
66
Bu
924
924
929
929
67
Bg
929
929
933
932
1.215e+41
4.1
1.366e+41
4.6
2.581e+41
8.8
68
Ag
933
933
941
933
1.245e+42
42.2
5.814e+40
2.0
1.303e+42
44.2
69
Bg
941
941
952
941
7.565e+40
2.6
8.832e+40
3.0
1.640e+41
5.6
70
Au
952
956
956
956
71
Bg
956
959
958
959
3.978e+40
1.3
5.104e+40
1.7
9.082e+40
3.1
72
Bu
959
997
981
1001
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.