calculateDensityMatrix¶
- calculateDensityMatrix(configuration, kpoint=None, spin=None)¶
Calculate the the Fourier component of the Density Matrix.
- Parameters:
configuration (
MoleculeConfiguration
|BulkConfiguration
|DeviceConfiguration
|SurfaceConfiguration
) – The configuration to use for the calculation.kpoint (tuple of floats) – The kpoint as three floats representing fractional reciprocal space coordinates. Default: The Gamma point
(0.0, 0.0, 0.0)
spin (
Spin.Up
|Spin.Down
|Spin.All
) – The spin component for which to perform the calculation. Default:Spin.All
- Returns:
The density matrix.
- Return type:
numpy.array
Usage Examples¶
Evaluate the density matrix of a BulkConfiguration.
density_matrix = calculateDensityMatrix(bulk_configuration)
Notes¶
Extract the Fourier transformed density matrix of a BulkConfiguration.
\[D({\bf k})_{\mu,\nu} = \sum_{n} f_n c^\dagger_\mu(n,{\bf k}) c_\nu(n,{\bf k}),\]where \(f_n\) are Fermi occupation factors and \(c_\nu(n,{\bf k})\) are basis function coefficients for eigenstate \(n, {\bf k}\) , i.e
\[H({\bf k}) {\bf c}(n, {\bf k}) = E_n S({\bf k}) {\bf c}(n, {\bf k})\]The calculator assigned to the device must be density matrix-based for this function to perform successfully.
Consider Spin for details on how to handle the spin parameter.