Tetragonal shear constant

Accurate ab initio methods for the calculation of elastic constants have been developed (Christensen 1984b), and a few calculations have been done for some cubic lanthanide and actinide systems (Soderlind etal. 1993, Wills etal. 1992). The tetragonal shear constant, C, is calculated as the second derivative of the total energy as a function of small tetragonal distortions. That is, the unit cell is stretched or compressed along the z-axis, while the cube edges in the x- and y-directions are varied equally by the amount necessary to conserve the volume of the unit cell. Both the bcc and fee structures may be considered to be body centred tetragonal (bet) with... 

Use the following values of the elastic-stiffness constants and the elastic-comphance constants (Kisi and Howard, 1998) for tetragonal zirconia monocrystals to determine the Voigt-Reuss-HiU averages for the Young s modulus, E, the shear modulus, G, and the bulk modulus, B. 

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