[Pw_forum] mixed 2nd derivatives - wrt atomic positions and strain

[Konstantin Kudin]

 Hi there,

 2nd derivatives wrt (with respect to) atomic positions twice are force
constants, and can be used to compute phonons.

 2nd derivatives wrt strain twice give stress tensor.

 Does anyone know a good reference where I could read about mixed 2nd
derivatives of these two?

 Thanks!
 Kostya

 
 


		
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