molecule.calculate_eigenmodes_linear_response_function

molecule.calculate_eigenmodes_linear_response_function()

Calculates the linear response function from the transition densities. This method does not calculate directly the linear response, but only the eigenmodes. The mathematics behind this function will soon be available somewhere…

Parameters:

None – All the data should be inside the molecule. Needs TD-DFT and molden properties

Returns:

• linear_response_eigenvalues – the eigenvalues of the linear response function

• linear_response_eigenvectors – the eigenvectors of the linear response function

Notes

The linear response function kernel can be computed as :

\(\chi(r,r') = -2\sum_{k\neq0} \frac{\rho_0^k(r) \rho_0^k(r')}{E_k-E_0}\)

With \(\rho_0^k\) the transition density, and \(E_k\) the energy of the transition k.

Therefore, the molecule needs the transition properties that can be extracted from a TD-DFT calculation, and the MO extracted from a molden file. More details can be found here.