-    MATLOCKITE     -    PbFCl

Experimental structure. Atomic position and lattice parameters 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:  129  P4/nmm 
Lattice parameters (Å):  4.1060  4.1060  7.2300 
Angles (°):  90.0  90.0  90.0 

Symmetry (theoretical): 

Space group:  129  P4/nmm 
Lattice parameters (Å):  4.1060  4.1060  7.2300 
Angles (°):  90.0  90.0  90.0 

Cell contents: 

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

Atomic positions (theoretical):

Pb:  0.0000  0.5000  0.2000 
F:  0.0000  0.0000  0.0000 
Cl:  0.0000  0.5000  0.6500 
Cl:  0.0000  0.0000  0.0000 
Cl:  0.0000  0.0000  0.0000 
Pb:  0.0000  0.0000  0.0000 
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): 

Pb: 3.7819 0.0000 0.0000 
0.0000 3.7818 0.0000 
-0.0000 -0.0000 3.3225 
Eig. Value: 3.7819 3.7818 3.3225 
F: -1.8057 -0.0000 0.0000 
-0.0000 -1.8057 -0.0000 
-0.0000 0.0000 -1.9627 
Eig. Value: -1.8057 -1.8057 -1.9627 
Cl: -1.9759 -0.0000 -0.0000 
-0.0000 -1.9759 -0.0000 
-0.0000 -0.0000 -1.3597 
Eig. Value: -1.9759 -1.9759 -1.3597 
Cl: -1.8062 0.0000 0.0000 
0.0000 -1.8062 0.0000 
0.0000 -0.0000 -1.9628 
Eig. Value: -1.8062 -1.8062 -1.9628 
Cl: 3.7818 -0.0000 -0.0000 
0.0000 3.7819 -0.0000 
0.0000 -0.0000 3.3225 
Eig. Value: 3.7818 3.7819 3.3225 
Pb: -1.9759 -0.0000 0.0000 
-0.0000 -1.9759 0.0000 
-0.0000 -0.0000 -1.3597 
Eig. Value: -1.9759 -1.9759 -1.3597 
Atom type 

Dielectric tensors: 

 
Ɛ5.0110 0.0000 0.0000 
0.0000 5.0110 0.0000 
0.0000 0.0000 4.3889 
Eig. Value: 5.0110 5.0110 4.3889 
Refractive index (N): 2.2385 0.0000 0.0000 
0.0000 2.2385 0.0000 
0.0000 0.0000 2.0950 
Eig. Value: 2.2385 2.2385 2.0950 
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