qml.qchem.mol_density_matrix

mol_density_matrix(n_electron, c)

Compute the molecular density matrix.

The density matrix \(P\) is computed from the molecular orbital coefficients \(C\) as

\[P_{\mu \nu} = \sum_{i=1}^{N} C_{\mu i} C_{\nu i},\]

where \(N = N_{electrons} / 2\) is the number of occupied orbitals. Note that the total density matrix is the sum of the \(\alpha\) and \(\beta\) density matrices, \(P = P^{\alpha} + P^{\beta}\).

Parameters

• n_electron (integer) – number of electrons

• c (array[array[float]]) – molecular orbital coefficients

Returns

density matrix

Return type

array[array[float]]

Example

>>> c = np.array([[-0.54828771,  1.21848441], [-0.54828771, -1.21848441]])
>>> n_electron = 2
>>> mol_density_matrix(n_electron, c)
array([[0.30061941, 0.30061941], [0.30061941, 0.30061941]])

code/api/pennylane.qchem.mol_density_matrix

 

Download Python script

 

Download Notebook

 

View on GitHub