unfold_s8_to_s4¶

unfold_s8_to_s4(eri, *, validate=True)[source]¶

Unfolds an 8-fold symmetric tensor to 4-fold symmetries (2-dimensional).

Parameters:

eri (Tensor | ndarray | SparseArray) – the 1-dimensional tensor to unfold.
validate (bool) – when set to False, the requirements of eri are not validated.

Returns:

A 4-fold symmetric tensor.

Raises:

ValueError – if eri is not 1-dimensional.

Return type:

S4Integrals