Problem with Orthorhombic stiffness matrix using CASTEP?

20 March 2025 1 945 Report

I have an orthorhombic crystalline system and I want to calculate its elastic constants.This system has 9 elastic constants C11,... C44, C55 and C66 while when I run the calculation I have 12 constants C11,...... C34 and I do not have the 9 constants!

I have tried with other Orthorhombic materials and it is the same thing.

Will someone be able to guide me?

thank y

NB:Attached is a paper on mechanical stability conditions with the matrix of orthorhombic systems.ou.

Philip James Hasnip

How are you computing the elastic constants? Are you using Materials Studio, or CASTEP's perturbation-theory-based calculator, or the old elastic constants script...?

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