molecule.calculate_transition_density

molecule.calculate_transition_density()

Calculates all the transition densities for a molecule If the MO were not calculated it will also calculate them

Parameters:

None – All the data should already be inside the molecule object

Returns:

transition_density_list

Notes

The transition densities are defined as

\(\rho_0^k = \sum_i c_i (Occ_i(r) * Virt_i(r))\)

With the sum being on all the transitions of the excitation, \(Occ_i(r)\) and \(Virt_i(r)\) being respectively the occupied and the virtual molecular orbitals considered in the transition, and \(c_i\) the coefficient of the transition.

Examples

For a TD-DFT calculation output :

STATE 1: E= 0.148431 au 4.039 eV

18a -> 20a : 0.5000 (c= 0.7071)

19a -> 21a : 0.5000 (c= -0.7071)

The transition density will be :

\(\rho_0^1 = c_1 (\psi_{18}(r) * \psi_{20}(r)) + c_2 (\psi_{19}(r) * \psi_{21}(r))\)

with \(c_1 = 0.7071\) and \(c_2 = -0.7071\)