- BASSANITE - CaSO₄0.625H₂O

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 Unstable structure.

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:	5		C2
Lattice parameters (Å):	17.5180	6.9291		12.0344
Angles (°):	90	133.655		90

Symmetry (theoretical):

Space group:	5		C2
Lattice parameters (Å):	9.3673	9.3673		12.0654
Angles (°):	50.18	129.81		136.42

Cell contents:

Number of atoms:	45
Number of atom types:	4
Chemical composition:	0

Atomic positions (theoretical):

Ca:	0.6262	0.9582	0.5754
Ca:	0.1863	0.5089	0.0572
Ca:	0.5056	0.5056	0.5000
Ca:	0.0017	0.0017	1.0000
S:	0.3965	0.2218	0.3122
S:	0.2525	0.7533	0.2457
S:	0.9157	0.7585	0.8053
O:	0.4002	0.3735	0.3212
O:	0.2814	0.2335	0.1514
O:	0.2935	0.9953	0.4153
O:	0.6256	0.2917	0.3608
O:	0.2974	0.9518	0.1104
O:	0.5802	0.2205	0.7606
O:	0.4345	0.7987	0.3882
O:	0.8621	0.5317	0.9066
O:	0.1522	0.8997	0.8322
O:	0.8473	0.8291	0.8357
O:	0.7910	0.7736	0.6422
O:	0.6800	0.0479	0.7549
O:	0.1644	0.1644	0.5000
O:	0.3529	0.6734	0.8873
H:	0.4625	0.8217	0.8422
H:	0.2956	0.5862	0.8348
H:	0.1133	0.0505	0.5876
Ca:	0.9582	0.6262	0.4246
Ca:	0.5089	0.1863	0.9428
S:	0.2218	0.3965	0.6878
S:	0.7533	0.2525	0.7543
S:	0.7585	0.9157	0.1947
O:	0.3735	0.4002	0.6788
O:	0.2335	0.2814	0.8486
O:	0.9953	0.2935	0.5847
O:	0.2917	0.6256	0.6392
O:	0.9518	0.2974	0.8896
O:	0.2205	0.5802	0.2394
O:	0.7987	0.4345	0.6118
O:	0.5317	0.8621	0.0934
O:	0.8997	0.1522	0.1678
O:	0.8291	0.8473	0.1643
O:	0.7736	0.7910	0.3578
O:	0.0479	0.6800	0.2451
O:	0.6734	0.3529	0.1127
H:	0.8217	0.4625	0.1578
H:	0.5862	0.2956	0.1652
H:	0.0505	0.1133	0.4124

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.

Dielectric Properties

We define:

The Born effective charges, also called dynamical charges, are tensors that correspond to the energy derivative with respect to atomic displacements and electric fields or, equivalently, to the change in atomic force due to an electric field: The sum of the Born effective charges of all nuclei in one cell must vanish, element by element, along each of the three directions of the space.
The dielectric tensors are the energy derivative with respect to two electric fields. They also relate the induced polarization to the external electric field.

Born effective charges (Z):

Ca:	2.3119	-0.1515	0.2862
	-0.1468	2.4274	0.2306
	0.2627	0.2500	2.4062
Eig. Value:	1.9315	2.5235	2.6906
Ca:	2.4283	-0.0301	0.1683
	-0.1478	2.4317	0.0294
	0.1158	0.1476	2.4154
Eig. Value:	2.5642	2.5022	2.2090
Ca:	2.5928	0.0000	-0.0036
	0.0000	2.1767	-0.0000
	0.0629	-0.0000	2.5004
Eig. Value:	2.6015	2.1767	2.4917
Ca:	2.6101	0.0000	-0.0409
	0.0000	1.9458	-0.0000
	0.0399	0.0000	2.6030
Eig. Value:	2.6101	1.9458	2.6029
S:	3.3790	-0.1701	0.1967
	-0.0496	3.4130	0.1571
	0.1839	0.1682	3.3430
Eig. Value:	3.5660	3.5072	3.0619
S:	3.6024	-0.0212	0.0499
	0.1456	3.1064	-0.0643
	0.1176	0.0420	3.5261
Eig. Value:	3.6602	3.0976	3.4770
S:	3.3536	-0.0478	0.2116
	-0.1367	3.4463	0.1243
	0.1716	0.0762	3.3252
Eig. Value:	3.5316	3.4990	3.0945
O:	-2.0621	0.4982	-0.0001
	0.4641	-1.1485	-0.0943
	0.0242	-0.0984	-1.0888
Eig. Value:	-2.2708	-0.9036	-1.1250
O:	-1.1189	0.1230	0.1343
	0.1042	-1.1140	-0.4771
	0.0965	-0.4310	-2.0857
Eig. Value:	-1.1211	-0.9136	-2.2839
O:	-1.0415	0.1722	-0.2664
	0.1959	-1.8946	0.5311
	-0.2677	0.4619	-1.3690
Eig. Value:	-0.8805	-2.2658	-1.1589
O:	-1.4878	-0.4321	-0.2646
	-0.5115	-1.7448	-0.2853
	-0.2566	-0.3216	-1.2376
Eig. Value:	-1.1356	-2.2611	-1.0734
O:	-1.1506	0.0249	-0.1480
	0.0357	-1.3319	0.6120
	-0.1884	0.5797	-1.8466
Eig. Value:	-1.1494	-0.9191	-2.2607
O:	-2.0703	-0.4784	0.0480
	-0.4492	-1.0750	0.0382
	0.0623	0.1207	-1.0925
Eig. Value:	-2.2585	-0.8785	-1.1007
O:	-1.1166	0.1335	0.0486
	0.0736	-1.2278	-0.5838
	-0.0148	-0.6273	-2.0354
Eig. Value:	-1.1424	-0.8747	-2.3627
O:	-1.3075	0.3845	-0.4675
	0.3619	-1.6398	0.4512
	-0.4296	0.4415	-1.3943
Eig. Value:	-1.1352	-2.3078	-0.8987
O:	-1.1123	-0.3600	-0.1688
	-0.3864	-2.0475	-0.2323
	-0.1520	-0.2413	-1.1122
Eig. Value:	-0.9353	-2.2459	-1.0908
O:	-2.2631	0.1093	0.1594
	0.2001	-0.9902	-0.1282
	0.1992	-0.1136	-1.1865
Eig. Value:	-2.3147	-0.9293	-1.1959
O:	-1.0878	0.0392	0.0728
	0.0809	-1.2112	-0.4419
	0.0305	-0.4014	-2.0584
Eig. Value:	-1.1029	-1.0177	-2.2369
O:	-1.8413	0.5740	0.0401
	0.5604	-1.5976	0.0467
	0.0632	0.0283	-1.1219
Eig. Value:	-2.2998	-1.1927	-1.0682
O:	-0.8690	0.0000	0.1511
	-0.0000	-0.9267	-0.0000
	0.1517	-0.0000	-1.0292
Eig. Value:	-0.7778	-0.9267	-1.1204
O:	-0.8929	0.0199	0.1218
	-0.0133	-1.2705	0.1023
	0.1289	0.0657	-0.8904
Eig. Value:	-1.0056	-1.2896	-0.7585
H:	0.3257	0.0057	-0.0113
	0.0714	0.9565	-0.2271
	-0.0331	-0.2213	0.4115
Eig. Value:	0.3182	1.0396	0.3359
H:	0.5631	-0.0975	-0.1441
	-0.0844	0.4809	0.0598
	-0.1261	0.0847	0.4336
Eig. Value:	0.7072	0.4237	0.3467
H:	0.4216	0.0715	-0.1203
	0.0792	0.4333	-0.1764
	-0.1153	-0.1312	0.6211
Eig. Value:	0.3675	0.3443	0.7643
Ca:	2.3119	0.1515	0.2862
	0.1468	2.4274	-0.2306
	0.2627	-0.2500	2.4062
Eig. Value:	1.9315	2.5235	2.6906
Ca:	2.4283	0.0301	0.1683
	0.1478	2.4317	-0.0294
	0.1158	-0.1476	2.4154
Eig. Value:	2.5642	2.5022	2.2090
S:	3.3790	0.1701	0.1967
	0.0496	3.4130	-0.1571
	0.1839	-0.1682	3.3430
Eig. Value:	3.5660	3.5072	3.0619
S:	3.6024	0.0212	0.0499
	-0.1456	3.1064	0.0643
	0.1176	-0.0420	3.5261
Eig. Value:	3.6602	3.0976	3.4770
S:	3.3536	0.0478	0.2116
	0.1367	3.4463	-0.1243
	0.1716	-0.0762	3.3252
Eig. Value:	3.5316	3.4990	3.0945
O:	-2.0621	-0.4982	-0.0001
	-0.4641	-1.1485	0.0943
	0.0242	0.0984	-1.0888
Eig. Value:	-2.2708	-0.9036	-1.1250
O:	-1.1189	-0.1230	0.1343
	-0.1042	-1.1140	0.4771
	0.0965	0.4310	-2.0857
Eig. Value:	-1.1211	-0.9136	-2.2839
O:	-1.0415	-0.1722	-0.2664
	-0.1959	-1.8946	-0.5311
	-0.2677	-0.4619	-1.3690
Eig. Value:	-0.8805	-2.2658	-1.1589
O:	-1.4878	0.4321	-0.2646
	0.5115	-1.7448	0.2853
	-0.2566	0.3216	-1.2376
Eig. Value:	-1.1356	-2.2611	-1.0734
O:	-1.1506	-0.0249	-0.1480
	-0.0357	-1.3319	-0.6120
	-0.1884	-0.5797	-1.8466
Eig. Value:	-1.1494	-0.9191	-2.2607
O:	-2.0703	0.4784	0.0480
	0.4492	-1.0750	-0.0382
	0.0623	-0.1207	-1.0925
Eig. Value:	-2.2585	-0.8785	-1.1007
O:	-1.1166	-0.1335	0.0486
	-0.0736	-1.2278	0.5838
	-0.0148	0.6273	-2.0354
Eig. Value:	-1.1424	-0.8747	-2.3627
O:	-1.3075	-0.3845	-0.4675
	-0.3619	-1.6398	-0.4512
	-0.4296	-0.4415	-1.3943
Eig. Value:	-1.1352	-2.3078	-0.8987
O:	-1.1123	0.3600	-0.1688
	0.3864	-2.0475	0.2323
	-0.1520	0.2413	-1.1122
Eig. Value:	-0.9353	-2.2459	-1.0908
O:	-2.2631	-0.1093	0.1594
	-0.2001	-0.9902	0.1282
	0.1992	0.1136	-1.1865
Eig. Value:	-2.3147	-0.9293	-1.1959
O:	-1.0878	-0.0392	0.0728
	-0.0809	-1.2112	0.4419
	0.0305	0.4014	-2.0584
Eig. Value:	-1.1029	-1.0177	-2.2369
O:	-1.8413	-0.5740	0.0401
	-0.5604	-1.5976	-0.0467
	0.0632	-0.0283	-1.1219
Eig. Value:	-2.2998	-1.1927	-1.0682
O:	-0.8929	-0.0199	0.1218
	0.0133	-1.2705	-0.1023
	0.1289	-0.0657	-0.8904
Eig. Value:	-1.0056	-1.2896	-0.7585
H:	0.3257	-0.0057	-0.0113
	-0.0714	0.9565	0.2271
	-0.0331	0.2213	0.4115
Eig. Value:	0.3182	1.0396	0.3359
H:	0.5631	0.0975	-0.1441
	0.0844	0.4809	-0.0598
	-0.1261	-0.0847	0.4336
Eig. Value:	0.7072	0.4237	0.3467
H:	0.4216	-0.0715	-0.1203
	-0.0792	0.4333	0.1764
	-0.1153	0.1312	0.6211
Eig. Value:	0.3675	0.3443	0.7643