qiskit.opflow.double_commutator

double_commutator(op_a, op_b, op_c, sign=False)

Compute symmetric double commutator of op_a, op_b and op_c. See McWeeny chapter 13.6 Equation of motion methods (page 479)

If sign is False, it returns

\[[[A, B], C]/2 + [A, [B, C]]/2 = (2ABC + 2CBA - BAC - CAB - ACB - BCA)/2.\]

If sign is True, it returns

\[\lbrace[A, B], C\rbrace/2 + \lbrace A, [B, C]\rbrace/2 = (2ABC - 2CBA - BAC + CAB - ACB + BCA)/2.\]

Parameters

• op_a (OperatorBase) – Operator A

• op_b (OperatorBase) – Operator B

• op_c (OperatorBase) – Operator C

• sign (bool) – False anti-commutes, True commutes

Returns

the double commutator

Return type

OperatorBase