The investigation of the mechanical properties was done by performing finite distortions of the lattice and deriving the elastic constants from the strain-stress relationship. The calculated sets of elastic constants C ij (i and j indicate directions) are given in Table . All C ij values are positive confirming the mechanical stability. Using ELATE program , introduced above, the bulk (B) and the shear (G) modules were obtained using Voigt's method; they are given in Table .