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Projekt Druckansicht

Modellierung von Ein- und Zweiphotonen-Spektroskopie in Lösung mit der Coupled-Cluster-Methode CC2 in Kombination mit Kontinuums- und atomistischen Einbettungsmodellen

Fachliche Zuordnung Theoretische Chemie: Elektronenstruktur, Dynamik, Simulation
Förderung Förderung von 2016 bis 2023
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 317213500
 
Erstellungsjahr 2023

Zusammenfassung der Projektergebnisse

Solvent or, in general, environment effects play an important role for many subjects in contemporary research in chemistry. This project addressed in particular the effects of an environment on spectroscopic properties with computational quantum chemistry tools. Until today most such calculations are done with timedependent density functional theory (TDDFT). Although computationally very efficient, TDDFT faces a number of limitations that are related to the semi-local functionals that are used today. Wavefunction-based methods provide an alternative approach with hierarchies of systematically improvable models. They are, however, less straightforward to combine with polarizable continuum solvation or atomistic embedding models. The objective of this project has been the development of an efficient and general implementation of the conductor-like solvation model (COSMO) and the atomistic polarizable embedding (PE) models for the correlated wavefunction methods CC2, ADC(2), CIS(D∞ ), and CIS(D), and their spin-component scaled SCS and SOS variants. The project started from preliminary implementations of COSMO-ADC(2) for the so-called perturbation to energy and density (PTED) reaction field scheme and PE-CC2 for a more efficient but theoretically less complete post-SCF reaction field scheme, both were restricted to closed-shell systems, were not parallelized, and restricted to a small set of functionalities. During the first part of the project we have generalized the implementation of the simpler and more efficient post-SCF reaction field scheme from PE-CC2 to the methods ADC(2), CIS(D∞), and CIS(D) and to the COSMO model for the methods CC2, ADC(2), CIS(D∞ ), and CIS(D). The COSMO implementation for excitation energies and UV/Vis and ECD spectra has been parallelized with OpenMP and MPI. At the COSMO-CC2 level we extended the functionalities to two-photon and MCD spectra. The most important development, however, has been the implementation of analytic excited-state gradients for PE-ADC(2) and COSMO-ADC(2). In addition to the extension of the implementation, a second focus of the project has been the evaluation of the accuracy and the reliability of the solvent models and, in particular, of different reaction field schemes for excitation energies with correlated wavefunction methods. Here, we have done benchmark study that compares the performance of the PTED and post-SCF reaction field schemes and applied the post-SCF scheme for the calculation of photoacidities to evaluate its performance for excited state structures by applying it to a set of fluorescence emission energies.

Projektbezogene Publikationen (Auswahl)

 
 

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