Orientation for the elastic data

The original reference for the elastic data [de Jong et al.,Sci.Data (2015)] reported the data using both “IEEE-format” and “the format corresponding to the orientation of the crystal structure as defined in the poscar-key”.
On the other hand, pymatgen’s SubstrateAnalyzer requires that the elastic data is provided “in the IEEE orientation”.

Can I safely assume that the data returned by API call to MP, for example by
MPRester().get_data(“mp-72”, prop=“elasticity”)[0][‘elasticity’][‘elastic_tensor’]
is always “in the IEEE orientation”, or should I be running additional checks/conversions before using that data with a substrate_analyzer?


Yes, the elastic tensor field should be in the IEEE orientation. The ‘elastic_tensor_original’ field is the raw, unsymmetrized, and unrotated tensor that is the direct result of the calculation in ‘poscar’ format.

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Thanks Joseph for clarifying this!

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I’m glad people are using this. :slight_smile: