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qiskit.opflow.double_commutator

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

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

If sign is True, it returns

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

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