Introduction to Solid State Physics · Problem 14

CRYSTAL BINDING AND ELASTIC CONSTANTS — Charles Kittel

Physics — Solid State · elastic-stability-criteria

Problem

Stability criteria. The criterion that a cubic crystal with one atom in the primitive cell be stable against small homogeneous deformations is that all the principal minors of the elastic energy matrix be positive. This requires that

C_{44} > 0

;

C_{11} > |C_{12}|

; and

C_{11} + 2C_{12} > 0

. Verify that the crystals listed in Table 11 satisfy these conditions.

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