-    TITANITE     -    CaTiSiO5

Theoretical atomic positions and lattice parameters at experimental volum from AMCSD. Computed using Teter "extended norm-conserving" pseudopotentials. 

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/c 
Lattice parameters (Å):  3.7402  4.6113  3.4725 
Angles (°):  90.0  113.8  90.0 

Symmetry (theoretical): 

Space group:  14  P2_1/c 
Lattice parameters (Å):  7.0617  8.6990  6.5950 
Angles (°):  90.0  114.2  90.0 

Cell contents: 

Number of atoms:  32 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

Ca:  0.2494  0.4210  0.2500 
Ti:  0.5003  0.2502  0.7499 
Si:  0.7499  0.4313  0.2499 
O:  0.7501  0.3160  0.7498 
O:  0.9054  0.3153  0.4369 
O:  0.0946  0.1847  0.0629 
O:  0.3855  0.4632  0.6534 
O:  0.6149  0.0370  0.8467 
Ca:  0.2506  0.9210  0.7500 
Ti:  0.9997  0.7502  0.2501 
Si:  0.7501  0.9313  0.7501 
O:  0.7499  0.8160  0.2502 
O:  0.5946  0.8153  0.5631 
O:  0.4054  0.6847  0.9371 
O:  0.1145  0.9632  0.3466 
O:  0.8851  0.5370  0.1533 
Ca:  0.7506  0.5790  0.7500 
Ti:  0.4997  0.7498  0.2501 
Si:  0.2501  0.5687  0.7501 
O:  0.2499  0.6840  0.2502 
O:  0.0946  0.6847  0.5631 
O:  0.9054  0.8153  0.9371 
O:  0.6145  0.5368  0.3466 
O:  0.3851  0.9630  0.1533 
Ca:  0.7494  0.0790  0.2500 
Ti:  0.0003  0.2498  0.7499 
Si:  0.2499  0.0687  0.2499 
O:  0.2501  0.1840  0.7498 
O:  0.4054  0.1847  0.4369 
O:  0.5946  0.3153  0.0629 
O:  0.8855  0.0368  0.6534 
O:  0.1149  0.4630  0.8467 
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: 2 2 4 
   number of shifts: 
   shifts: 0.5 0.5 0.5 
Kinetic energy cut-off: 32/54 Ha  [=870.7712 eV ]
eXchange-Correlation functional: LDA pw90 

Pseudopotentials: 
Ca:  calcium, fhi98PP : Trouiller-Martins-type, LDA Ceperley/Alder Perdew/Wang (1992), l= 0 local 
Ti:  Titane.ion 3s2.3p6.4s0.3d2 rcd=1.65, rcs=rc0=1.25, ecut 32/54 
Si:  silicon, 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