Symmetric 2-body electronic integrals (qiskit_nature.second_q.operators.symmetric_two_body)

This module provides utilities to deal with symmetry-reduced 2-body electronic integrals.

Container classes

The classes provided here extend the numpy.ndarray interface and, thus, may be used as such interchangeably.

Note

Some operations may not be available on the symmetry-reduced space in which case the instance will automatically be unfolded to the full 4-dimensional array. After a successful operation, the original symmetry will be attempted to be restored.

SymmetricTwoBodyIntegrals

An abstract base class providing the interface for symmetry-reduced two-body electronic integral container classes.

S1Integrals

A container for 1-fold symmetric 2-body electronic integrals in chemist ordering.

S4Integrals

A container for 4-fold symmetric 2-body electronic integrals in chemist ordering.

S8Integrals

A container for 8-fold symmetric 2-body electronic integrals in chemist ordering.

Unfolding methods

These methods can be used to unfold higher symmetries to lower ones.

Note

This implies that the memory consumption increases.

unfold(eri, *[, validate])

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

unfold_s4_to_s1(eri, *[, validate])

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

unfold_s8_to_s1(eri, *[, validate])

Unfolds an 8-fold symmetric tensor to 1-fold symmetries (4-dimensional).

unfold_s8_to_s4(eri, *[, validate])

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

Folding methods

These methods can be used to fold lower symmetries to higher ones.

Note

This implies that the memory consumption decreases.

fold(eri, *[, validate])

Folds an electronic integrals tensor.

fold_s1_to_s4(eri, *[, validate])

Folds a 4-dimensional tensor to 4-fold symmetries (2-dimensional).

fold_s1_to_s8(eri, *[, validate])

Folds a 4-dimensional tensor to 8-fold symmetries (1-dimensional).

fold_s4_to_s8(eri, *[, validate])

Folds a 2-dimensional tensor to 8-fold symmetries (1-dimensional).