- GYPSUM - CaSO₄2(H₂O)

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:	15		C2/c
Lattice parameters (Å):	3.3216	8.0334		3.0015
Angles (°):	90	114.11		90

Symmetry (theoretical):

Space group:	15		C2/c
Lattice parameters (Å):	8.1627	8.1627		5.6647
Angles (°):	80.91	99.08		45.67

Cell contents:

Number of atoms:	24
Number of atom types:	4
Chemical composition:	0

Atomic positions (theoretical):

Ca:	0.1682	0.1682	0.2500
S:	0.3299	0.3299	0.7500
O:	0.3600	0.1889	0.5930
O:	0.5835	0.1877	0.9157
O:	0.8623	0.2727	0.9146
H:	0.8353	0.3399	0.7340
H:	0.7629	0.2445	0.9083
O:	0.1889	0.3600	0.9070
O:	0.1877	0.5835	0.5843
O:	0.2727	0.8623	0.5854
H:	0.3399	0.8353	0.7660
H:	0.2445	0.7629	0.5917
Ca:	0.8318	0.8318	0.7500
S:	0.6701	0.6701	0.2500
O:	0.6400	0.8111	0.4070
O:	0.4165	0.8123	0.0843
O:	0.1377	0.7273	0.0854
H:	0.1647	0.6601	0.2660
H:	0.2371	0.7555	0.0917
O:	0.8111	0.6400	0.0930
O:	0.8123	0.4165	0.4157
O:	0.7273	0.1377	0.4146
H:	0.6601	0.1647	0.2340
H:	0.7555	0.2371	0.4083

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	Bg	92	92	92	92	2.545e+38 0.2	2.752e+38 0.2	5.297e+38 0.4
5	Bu	95	96	95	95
6	Ag	103	103	103	103	1.262e+39 0.9	9.725e+38 0.7	2.234e+39 1.5
7	Au	106	106	107	106
8	Bg	113	113	113	113	6.536e+37 0.0	8.987e+37 0.1	1.552e+38 0.1
9	Bu	113	117	113	113
10	Bg	117	129	117	117	5.954e+38 0.4	7.182e+38 0.5	1.314e+39 0.9
11	Ag	129	131	129	129	8.768e+38 0.6	7.485e+38 0.5	1.625e+39 1.1
12	Ag	139	139	139	139	1.758e+39 1.2	2.004e+39 1.4	3.762e+39 2.5
13	Bg	145	145	145	145	1.840e+38 0.1	2.734e+38 0.2	4.574e+38 0.3
14	Bg	158	158	158	158	5.923e+38 0.4	7.299e+38 0.5	1.322e+39 0.9
15	Bu	169	170	169	170
16	Au	170	170	172	172
17	Bg	172	172	173	175	5.596e+38 0.4	9.422e+38 0.6	1.502e+39 1.0
18	Ag	184	184	184	184	3.263e+39 2.2	1.486e+39 1.0	4.748e+39 3.2
19	Bu	187	189	187	192
20	Au	196	196	200	196
21	Bg	200	200	206	200	6.147e+38 0.4	6.583e+38 0.4	1.273e+39 0.9
22	Bu	206	220	211	207
23	Ag	220	226	220	220	8.592e+38 0.6	4.549e+38 0.3	1.314e+39 0.9
24	Au	226	230	230	226
25	Bg	230	231	232	230	5.977e+38 0.4	8.792e+38 0.6	1.477e+39 1.0
26	Bu	232	272	247	266
27	Au	335	335	345	335
28	Bu	345	345	348	351
29	Ag	351	351	351	352	1.219e+39 0.8	8.514e+38 0.6	2.070e+39 1.4
30	Bg	360	360	360	360	3.708e+38 0.3	4.388e+38 0.3	8.096e+38 0.5
31	Ag	400	400	400	400	8.743e+39 5.9	6.617e+39 4.5	1.536e+40 10.4
32	Au	403	403	404	403
33	Ag	470	470	470	470	8.097e+39 5.5	6.161e+39 4.2	1.426e+40 9.6
34	Au	479	479	479	479
35	Bu	480	512	480	481
36	Bg	542	542	542	542	1.895e+39 1.3	2.244e+39 1.5	4.140e+39 2.8
37	Au	548	548	548	548
38	Bu	552	571	552	555
39	Ag	582	582	582	582	5.503e+39 3.7	5.698e+39 3.9	1.120e+40 7.6
40	Au	587	587	593	587
41	Bg	593	593	593	593	2.996e+39 2.0	4.674e+39 3.2	7.670e+39 5.2
42	Bu	614	619	614	623
43	Bg	637	637	637	637	1.761e+39 1.2	1.919e+39 1.3	3.680e+39 2.5
44	Ag	646	646	646	646	2.170e+39 1.5	1.634e+39 1.1	3.804e+39 2.6
45	Bu	648	657	648	650
46	Bg	657	669	657	657	1.197e+39 0.8	1.851e+39 1.3	3.048e+39 2.1
47	Bg	669	674	669	669	3.722e+38 0.3	4.302e+38 0.3	8.024e+38 0.5
48	Au	674	683	683	674
49	Ag	683	686	685	683	8.821e+38 0.6	6.750e+38 0.5	1.557e+39 1.1
50	Bu	715	717	715	719
51	Au	736	736	740	736
52	Ag	762	762	762	762	2.328e+39 1.6	1.210e+39 0.8	3.538e+39 2.4
53	Au	972	972	974	972
54	Ag	977	977	977	977	1.259e+41 85.1	5.519e+37 0.0	1.259e+41 85.2
55	Bg	1073	1073	1073	1073	6.959e+39 4.7	7.400e+39 5.0	1.436e+40 9.7
56	Bu	1074	1077	1074	1092
57	Au	1092	1092	1122	1114
58	Ag	1122	1122	1122	1122	4.478e+39 3.0	5.645e+39 3.8	1.012e+40 6.8
59	Bu	1122	1128	1128	1128
60	Bg	1128	1191	1167	1151	1.160e+40 7.8	1.895e+40 12.8	3.056e+40 20.7
61	Bu	1566	1566	1566	1576
62	Ag	1579	1579	1579	1579	7.108e+38 0.5	4.414e+38 0.3	1.152e+39 0.8
63	Bg	1641	1641	1641	1641	1.290e+38 0.1	1.907e+38 0.1	3.198e+38 0.2
64	Au	1644	1644	1647	1644
65	Bg	3263	3263	3263	3263	8.024e+39 5.4	1.322e+40 8.9	2.125e+40 14.4
66	Bu	3264	3264	3264	3264
67	Bu	3264	3265	3264	3276
68	Ag	3276	3276	3276	3331	9.876e+40 66.8	2.348e+40 15.9	1.222e+41 82.7
69	Bu	3372	3377	3372	3372
70	Ag	3378	3378	3378	3378	1.267e+41 85.7	2.121e+40 14.3	1.479e+41 100.0
71	Bg	3391	3391	3391	3391	1.053e+40 7.1	1.148e+40 7.8	2.200e+40 14.9
72	Au	3427	3427	3492	3427

No.

Char.

ω TO

ω LOx

ω LOy

ω LOz

I ∥

I ⊥