qml.qchem.fermionic_observable

fermionic_observable(constant, one=None, two=None, cutoff=1e-12)

Create a fermionic observable from molecular orbital integrals.

Parameters

• constant (array[float]) – the contribution of the core orbitals and nuclei

• one (array[float]) – the one-particle molecular orbital integrals

• two (array[float]) – the two-particle molecular orbital integrals

• cutoff (float) – cutoff value for discarding the negligible integrals

Returns

fermionic observable

Return type

FermiSentence

Example

>>> constant = np.array([1.0])
>>> integral = np.array([[0.5, -0.8270995], [-0.8270995, 0.5]])
>>> fermionic_observable(constant, integral)
1.0 * I
+ 0.5 * a⁺(0) a(0)
+ -0.8270995 * a⁺(0) a(2)
+ 0.5 * a⁺(1) a(1)
+ -0.8270995 * a⁺(1) a(3)
+ -0.8270995 * a⁺(2) a(0)
+ 0.5 * a⁺(2) a(2)
+ -0.8270995 * a⁺(3) a(1)
+ 0.5 * a⁺(3) a(3)

code/api/pennylane.qchem.fermionic_observable

 

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