shape of stress when using LinearCombinationCalculator
When the prop is "stress" in the above code, the shape of the stress tensor may be inconsistent sometimes among self.calcs, to yield the error "ValueError: operands could not be broadcast together with shapes (3,3) (6,) " . For example, when using the SumCalculator with VASP and DFT-D3, it will occur. Also, the same issue is mentioned at https://github.com/dftd4/dftd4/issues/59 . It would be great that full_3x3_to_voigt_6_stress or voigt_6_to_full_3x3_stress will be called when prop == "stress".