Abstract
Photoactive systems are characterized by their capacity to absorb the energy of light and transform it. Usually, more than one chromophore is involved in the light absorption and excitation transport processes in complex systems. Linear-Response Time-Dependent Density Functional (LR-TDDFT) is commonly used to identify excitation energies and transition properties by solving the well-known Casida’s equation for single molecules. However, in practice, LR-TDDFT presents some disadvantages when dealing with multichromophore systems due to the increasing size of the electron–hole pairwise basis required for accurate evaluation of the absorption spectrum. In this work, we extend our local density decomposition method that enables us to disentangle individual contributions into the absorption spectrum to computation of exciton dynamic properties, such as exciton coupling parameters. We derive an analytical expression for the transition density from Real-Time Propagation TDDFT (P-TDDFT) based on Linear Response theorems. We demonstrate the validity of our method to determine transition dipole moments, transition densities, and exciton coupling for systems of increasing complexity. We start from the isolated benzaldehyde molecule, perform a distance analysis for π-stacked dimers, and finally map the exciton coupling for a 14 benzaldehyde cluster.
Highlights
In the last decades, the interest in using natural sun light for an energy transition toward green and clean energy sources has increased
We demonstrate that treating all the complex photoactive systems at the ab initio level of theory allows for accurate calculations of the exciton dynamic properties
We validated that the transition dipole moment can be obtained by Gaussian fitting of the absorption spectra, and its direction is recovered from the eigenvectors of the dynamic polarizability diagonalization
Summary
The interest in using natural sun light for an energy transition toward green and clean energy sources has increased. It has been demonstrated that P-TDDFT is an excellent platform for studies of such properties and processes such as molecular[24] and electron[25] dynamics, linear and nonlinear optics,[26] transport properties,[27] single and triplet excitations,[28,29] dynamical hyperpolarizabilites,[30] and exciton decay dynamics.[31] But probably, the most useful advantage that P-TDDFT offers is the possibility to obtain all frequency excitations at the same cost having converged just the occupied KS states for the ground state.[32,33] propagation of the KS states can be highly parallelized enabling us to compute optical properties for up to several thousands of atoms.[34,35] These features make P-TDDFT the suitable theoretical framework to study photoactive complex systems such as natural LHC and OLEDS. We first describe the methodology developed and discuss the results for the systems listed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
