-    GYPSUM     -    CaSO42(H2O)

 

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: 
Chemical composition: 

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: 

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.
 

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: 2.6253 -0.0001 -0.1027 
0.0001 2.1527 0.0004 
0.0159 0.0002 2.3034 
Eig. Value: 2.6310 2.1527 2.2976 
S: 3.5871 0.0010 0.0477 
0.0010 3.3740 0.0009 
0.1092 0.0007 3.3817 
Eig. Value: 3.6136 3.3740 3.3551 
O: -1.5664 0.4049 0.3882 
0.4692 -1.4237 -0.5533 
0.4052 -0.5490 -1.4393 
Eig. Value: -2.3998 -1.1521 -0.8774 
O: -1.4143 -0.4260 -0.3168 
-0.4247 -1.5395 -0.5259 
-0.3610 -0.5079 -1.5418 
Eig. Value: -0.9969 -2.3654 -1.1332 
O: -0.9467 -0.1252 0.0032 
-0.1262 -1.2659 0.1132 
0.0176 0.0585 -1.2420 
Eig. Value: -0.9021 -1.3669 -1.1855 
H: 0.3678 0.0169 -0.0469 
0.0600 0.4177 -0.3351 
-0.1494 -0.3096 1.0778 
Eig. Value: 0.3548 0.2864 1.2221 
H: 0.4484 0.2193 -0.0007 
0.1581 1.0408 -0.0586 
0.0246 0.0318 0.2971 
Eig. Value: 0.3957 1.0959 0.2946 
O: -1.5686 -0.4049 0.3881 
-0.4693 -1.4253 0.5530 
0.4049 0.5489 -1.4389 
Eig. Value: -2.4007 -1.1538 -0.8784 
O: -1.4114 0.4255 -0.3166 
0.4243 -1.5343 0.5259 
-0.3607 0.5078 -1.5399 
Eig. Value: -0.9931 -2.3615 -1.1310 
O: -0.9375 0.1253 0.0043 
0.1262 -1.2583 -0.1141 
0.0189 -0.0590 -1.2367 
Eig. Value: -0.8931 -1.3610 -1.1784 
H: 0.3686 -0.0168 -0.0465 
-0.0601 0.4187 0.3360 
-0.1493 0.3101 1.0807 
Eig. Value: 0.3557 0.2872 1.2251 
H: 0.4495 -0.2197 -0.0007 
-0.1584 1.0425 0.0584 
0.0246 -0.0318 0.2983 
Eig. Value: 0.3967 1.0977 0.2958 
Ca: 2.6239 -0.0001 -0.1029 
-0.0001 2.1530 0.0002 
0.0156 0.0003 2.3027 
Eig. Value: 2.6297 2.1530 2.2969 
S: 3.5843 0.0007 0.0481 
0.0005 3.3711 0.0008 
0.1095 0.0006 3.3801 
Eig. Value: 3.6112 3.3711 3.3532 
O: -1.5673 0.4052 0.3882 
0.4697 -1.4254 -0.5544 
0.4053 -0.5503 -1.4408 
Eig. Value: -2.4023 -1.1534 -0.8778 
O: -1.4235 -0.4265 -0.3175 
-0.4250 -1.5444 -0.5266 
-0.3619 -0.5090 -1.5496 
Eig. Value: -1.0026 -2.3739 -1.1411 
O: -0.9370 -0.1251 0.0040 
-0.1259 -1.2620 0.1133 
0.0184 0.0585 -1.2335 
Eig. Value: -0.8933 -1.3614 -1.1778 
H: 0.3686 0.0168 -0.0468 
0.0600 0.4188 -0.3350 
-0.1492 -0.3092 1.0789 
Eig. Value: 0.3557 0.2877 1.2230 
H: 0.4496 0.2208 -0.0006 
0.1592 1.0447 -0.0582 
0.0248 0.0323 0.2980 
Eig. Value: 0.3965 1.1003 0.2956 
O: -1.5698 -0.4063 0.3885 
-0.4703 -1.4260 0.5532 
0.4052 0.5491 -1.4389 
Eig. Value: -2.4025 -1.1537 -0.8784 
O: -1.4162 0.4259 -0.3183 
0.4243 -1.5363 0.5260 
-0.3622 0.5086 -1.5451 
Eig. Value: -0.9964 -2.3668 -1.1343 
O: -0.9334 0.1253 0.0042 
0.1261 -1.2559 -0.1136 
0.0186 -0.0587 -1.2308 
Eig. Value: -0.8892 -1.3569 -1.1739 
H: 0.3690 -0.0168 -0.0467 
-0.0600 0.4193 0.3353 
-0.1492 0.3094 1.0799 
Eig. Value: 0.3561 0.2880 1.2241 
H: 0.4499 -0.2202 -0.0008 
-0.1587 1.0436 0.0582 
0.0246 -0.0321 0.2988 
Eig. Value: 0.3969 1.0991 0.2964 
Atom type 

Dielectric tensors: 

 
Ɛ2.3850 0.0000 0.0000 
0.0000 2.4043 0.0000 
0.0000 0.0000 2.4091 
Eig. Value: 2.3842 2.4043 2.4099 
Refractive index (N): 1.5443 -0.0000 -0.0000 
-0.0000 1.5506 -0.0000 
-0.0000 -0.0000 1.5521 
Eig. Value: 1.5441 1.5506 1.5524 
Ɛ00.0000 0.0000 0.0000 
0.0000 0.0000 0.0000 
0.0000 0.0000 0.0000 
Eig. Value: 0.0000 0.0000 0.0000