unfold_s4_to_s1

unfold_s4_to_s1(eri, *, validate=True)

Unfolds an 4-fold symmetric tensor to 1-fold symmetries (4-dimensional).

Parameters:

• eri (Tensor | ARRAY_TYPE) – the 2-dimensional tensor to unfold.

• validate (bool) – when set to False, the requirements of eri are not validated.

Returns:

A 1-fold symmetric tensor.

Raises:

ValueError – if eri is not 2-dimensional.

Return type:

S1Integrals