7.9 Correlated Excited State Methods: The ADC(n) Family

7.9.6 Properties and Visualization

The calculation of excited states using the ADCman module yields by default the usual excitation energies and the excitation amplitudes, as well as the transition dipole moments, oscillator strengths, and the norm of the doubles part of the amplitudes (if applicable). In addition, the calculation of excited state properties, like dipole moments, and transition properties between excited states can be requested by setting the $rem variables ADC_PROP_ES and ADC_PROP_ES2ES, respectively. Resonant two-photon absorption cross-sections of the excited states can be computed as well, using either sum-over-states expressions or the matrix inversion technique. The calculation via sum-over-state expressions is automatically activated, if ADC_PROP_ES2ES is set. The accuracy of the results, however, strongly depends on the number of states which are included in the summation, i.e. the number of states computed. At least, 20-30 excited states (per irreducible representation) are required to yield useful results for the two-photon absorption cross-sections. Alternatively, the resonant two-photon absorption cross-sections can be calculated by setting ADC_PROP_TPA to TRUE. In this case, the computation of a large number of excited states is avoided and there is no dependence on the number of excited states. Instead, an additional linear matrix equation has to be solved for every excited state for which the two-photon absorption cross-section is computed. Thus, the obtained resonant two-photon absorption cross-sections are usually more reliable. The quantity printed out is the microscopic cross-section (also known as rotationally averaged 2PA strength). Specifically, the value 30×δTPm is printed out where δTPm is defined in Eq. (13) of Ref. 1006. The quantity printed out is the microscopic cross-section (also known as rotationally averaged 2PA strength). Specifically, the value 30×δTPm is printed out where δTPm is defined in Eq. (13) of Ref. 1006.

Furthermore, the ADCman module allows for the detailed analysis of the excited states and export of various types of excited state related orbitals and densities. This can be activated by setting the keyword STATE_ANALYSIS. Details on the available analyses and export options can be found in section 11.2.6.