Ramon Cuadrado del Burgo - March 7, 2016   

  The present test performs fully-relativistic simulation of FePt-L1_0 structure 
placed with the (001) axis along X and Z, X-alignment and Z-alignment, respectively. 
By means of the calculation of the total selfconsistent energy it is possible to 
obtain the magnetic anisotropy energy (MAE) checking in addition that:

 * X-alignment:

   1)  The total SC energy for x-axis spin orientation corresponds to the 
      lower value: E_x < E_y = E_z => x-axis = Easy axis    

   2)  The total SC energy for y-axis and z-axis spin orientation have the 
      same value and they are larger than x-axis SC total energy: 
      E_y = E_z => y/z-axis = Hard axes         

 * Z-alignment:

   1)  The total SC energy for z-axis spin orientation corresponds to the 
      lower value: E_z < E_x = E_y => z-axis = Easy axis    

   2)  The total SC energy for x-axis and y-axis spin orientation have the 
      same value and they are larger than z-axis SC total energy: 
      E_x = E_y => x/y-axis = Hard axes         

 For comparison of (X/Z)-alignment, the total SC energies and MAEs of both 
configurations have to have the same values when the system is rotated in space:

    a) E_x(X-alignment) = E_z(Z-alignment)
       E_y(X-alignment) = E_x(Z-alignment)   
       E_z(X-alignment) = E_y(Z-alignment)   
 
    b) MAE(X-alignment) = E_x - E_(y/z) <=> MAE(Z-alignment) = E_z - E_(x/y)
