Definition of ASE stress vs deepmd virial

[romankempt]

Hi, I'm not familiar with the key difference between the stress in voigt notation and the virial tensor.

I've noticed that here in the dpdata ase plugin, they differ by a factor of the negative volume.

So if I wish to parse data from the ASE to a deepmd LabeledSystem, do I have to define the virial as:

virials = atoms.get_stress(voigt=False)

or

stress = atoms.get_stress(voigt=False)
virials = np.array([-atoms.get_volume() * stress]).astype('float32')

Thanks in advance!

[njzjz]

Yes, you can see discussion in #338.

[romankempt]

I see, thanks! :)