Analytische Näherung für elastische Wellen in anisotropen kubischen Kristallen

It is shown that the frequencies ω_α(k) and the polarisation vectorse _α(k) (α=1, 2, 3) of the elastic waves in anisotropic cubic crystals can be described exactly as Taylor series in the parameter \(\delta = \frac{{c_{11} - c_{12} - 2c_{44} }}{{c_{12} + c_{44} }}\) for all wave number vectorsk. As the expansion functions of these series include no elastic constants, δ is taken as the proper anisotropy parameter. The series are converging very fast for almost all substances and may be broken off after the third expansion term.