-    VUAGNATITE     -    CaAlSiO4(OH)

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:  19  P2_12_12_1 
Lattice parameters (Å):  7.0550  8.5420  5.6830 
Angles (°):  90  90  90 

Symmetry (theoretical): 

Space group:  19  P2_12_12_1 
Lattice parameters (Å):  7.0561  8.5340  5.6875 
Angles (°):  90  90  90 

Cell contents: 

Number of atoms:  36 
Number of atom types:  5 
Chemical composition:  0 

Atomic positions (theoretical):

Ca:  0.3656  0.6660  0.0296 
Al:  0.2652  0.9936  0.7391 
Si:  0.6239  0.8103  0.5125 
O:  0.4343  0.9283  0.4942 
O:  0.7932  0.9313  0.5680 
O:  0.6515  0.7101  0.2699 
O:  0.6186  0.6936  0.7410 
O:  0.3927  0.9402  0.0048 
:  0.5239  0.9983  0.0203 
Ca:  0.1344  0.3340  0.5296 
Al:  0.2348  0.0064  0.2391 
Si:  0.8761  0.1897  0.0125 
O:  0.0657  0.0717  0.9942 
O:  0.7068  0.0687  0.0680 
O:  0.8485  0.2899  0.7699 
O:  0.8814  0.3064  0.2410 
O:  0.1073  0.0598  0.5048 
:  0.9761  0.0017  0.5203 
Ca:  0.6344  0.1660  0.4704 
Al:  0.7348  0.4936  0.7609 
Si:  0.3761  0.3103  0.9875 
O:  0.5657  0.4283  0.0058 
O:  0.2068  0.4313  0.9320 
O:  0.3485  0.2101  0.2301 
O:  0.3814  0.1936  0.7590 
O:  0.6073  0.4402  0.4952 
:  0.4761  0.4983  0.4797 
Ca:  0.8656  0.8340  0.9704 
Al:  0.7652  0.5064  0.2609 
Si:  0.1239  0.6897  0.4875 
O:  0.9343  0.5717  0.5058 
O:  0.2932  0.5687  0.4320 
O:  0.1515  0.7899  0.7301 
O:  0.1186  0.8064  0.2590 
O:  0.8927  0.5598  0.9952 
:  0.0239  0.5017  0.9797 
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.
 

Parameters of the Calculation 


All the calculations have been done using the ABINIT software. This is a list of the most representative parameteres used during the Raman calculation.


Number of electronic bands: 26
k-points  
   grid: 2 2 4 
   number of shifts: 1 
   shifts: 0.5 0.5 0.5 
Kinetic energy cut-off: 40 Ha  [=1088.464 eV ]
eXchange-Correlation functional: LDApw90 

Pseudopotentials: 
Ca:  calcium, fhi98PP : Trouiller-Martins-type, LDA Ceperley/Alder Perdew/Wang (1992), l= 0 local 
Al:  aluminium, fhi98PP : Trouiller-Martins-type, LDA Ceperley/Alder Perdew/Wang (1992), l= 2 local 
Si:  silicon, fhi98PP : Trouiller-Martins-type, LDA Ceperley/Alder Perdew/Wang (1992), l= 2 local 
O:  oxygen, fhi98PP : Trouiller-Martins-type, GGA Perdew/Burke/Ernzerhof (1996), l= 2 local 
: