-    METAVARISCITE     -    AlPO4.2H2O

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 

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):  5.1780  9.5140  8.4540 
Angles (°):  90.0  90.3  90.0 

Symmetry (theoretical): 

Space group:  14  P2_1/n 
Lattice parameters (Å):  5.0607  9.5198  8.2031 
Angles (°):  90.0  91.6  90.0 

Cell contents: 

Number of atoms:  48 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

Al:  0.4036  0.3218  0.2932 
P:  0.9072  0.1400  0.1794 
O:  0.1807  0.1697  0.2557 
O:  0.8742  0.2114  0.0136 
O:  0.6972  0.2005  0.2911 
O:  0.8785  0.9803  0.1655 
O:  0.1108  0.4360  0.2771 
O:  0.4469  0.3509  0.0713 
H:  0.1614  0.5370  0.2543 
H:  0.9220  0.4345  0.3111 
H:  0.3098  0.3350  0.9839 
H:  0.6162  0.3124  0.0293 
Al:  0.0964  0.8218  0.2068 
P:  0.5928  0.6400  0.3206 
O:  0.3193  0.6697  0.2443 
O:  0.6258  0.7114  0.4864 
O:  0.8028  0.7005  0.2089 
O:  0.6215  0.4803  0.3345 
O:  0.3892  0.9360  0.2229 
O:  0.0531  0.8509  0.4287 
H:  0.3386  0.0370  0.2457 
H:  0.5780  0.9345  0.1889 
H:  0.1902  0.8350  0.5161 
H:  0.8838  0.8124  0.4707 
Al:  0.5964  0.6782  0.7068 
P:  0.0928  0.8600  0.8206 
O:  0.8193  0.8303  0.7443 
O:  0.1258  0.7886  0.9864 
O:  0.3028  0.7995  0.7089 
O:  0.1215  0.0197  0.8345 
O:  0.8892  0.5640  0.7229 
O:  0.5531  0.6491  0.9287 
H:  0.8386  0.4630  0.7457 
H:  0.0780  0.5655  0.6889 
H:  0.6902  0.6650  0.0161 
H:  0.3838  0.6876  0.9707 
Al:  0.9036  0.1782  0.7932 
P:  0.4072  0.3600  0.6794 
O:  0.6807  0.3303  0.7557 
O:  0.3742  0.2886  0.5136 
O:  0.1972  0.2995  0.7911 
O:  0.3785  0.5197  0.6655 
O:  0.6108  0.0640  0.7771 
O:  0.9469  0.1491  0.5713 
H:  0.6614  0.9630  0.7543 
H:  0.4220  0.0655  0.8111 
H:  0.8098  0.1650  0.4839 
H:  0.1162  0.1876  0.5293 
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.
 

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: 4 1 2 
   number of shifts: 
   shifts: 0.5 0.5 0.5 
Kinetic energy cut-off: 40 Ha  [=1088.464 eV ]
eXchange-Correlation functional: LDA pw90 

Pseudopotentials: 
Al:  aluminium, fhi98PP : Trouiller-Martins-type, LDA Ceperley/Alder Perdew/Wang (1992), l= 2 local 
P:  phosphorus, fhi98PP : Trouiller-Martins-type, LDA Ceperley/Alder Perdew/Wang (1992), l= 2 local 
O:  oxygen, fhi98PP : Trouiller-Martins-type, LDA Ceperley/Alder Perdew/Wang (1992), l= 2 local 
H:  hydrogen, fhi98PP : Trouiller-Martins-type, LDA Ceperley/Alder Perdew/Wang (1992), l= 2 local