First Principle Calculations of Two-Photon Absorption Spectra: trans-Octatetraene and trans-Stilbene

摘要

An accurate prediction of two-photon absorption (TPA) spectra would be of value in the design of TPA molecules for specific applications. The spectrum can be calculated using the sum-over-states (SOS) formalism, which requires accurate values for the energies of the relevant electronic states and for the transition dipole moments between these states. Time-Dependent Density Functional Theory (TDDFT) has been shown to give accurate excitation energies and ground-state transition dipole moments for a wide variety of molecules. It is now possible to use this method to calculate excited-state transition dipole moments and to subsequently calculate TPA cross-sections using the SOS formalism. We report TDDFT calculations of the TPA spectra for trans-octatetraene and trans-stilbene. The energy levels, transition dipole moments, and TPA cross-sections calculated by this and other methods are compared to experiment and to other theoretical methods.