First-Principles Studies of the Excited States of Chromophore Monomers and Dimers

ORAL

Abstract

Elucidation of the energy transfer mechanism in natural photosynthetic systems remains an exciting challenge. Through the careful analysis of excited states on individual chromophores and dimers -- and the predictive first-principles methods used to compute them -- we are building towards an understanding of the nature of excitation transfer among arrays of chromophores embedded in protein environments. Excitation energies, transition dipoles, and natural transition orbitals for the important low-lying singlet and triplet states of experimentally-relevant chromophores are obtained from first-principles time-dependent density functional theory (TDDFT) and many body perturbation theory. The effect of the Tamm-Dancoff approximation and the performance of several exchange-correlation functionals, including an optimally-tuned range-separated hybrid, are evaluated with TDDFT, and compared to MBPT calculations and experiments. This work has been supported by the DOE; computational resources have been provided by NERSC.

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Authors

  • Samia Hamed

    University of California at Berkeley

  • Sahar Sharifzadeh

    Boston University, Dept. of Electrical and Computer Engineering, Boston University

  • Jeffrey Neaton

    Univ of California - Berkeley, Molecular Foundry, Lawrence Berkeley National Laboratory, Physics Department, UC Berkeley \& Molecular Foundry, LBNL \& Kavli Energy NanoSciences Institute at Berkeley, Berkeley, University of California at Berkeley, University of California, Berkeley; Lawrence Berkeley National Laboratory, Dept. of Physics, UC Berkeley, Molecular Foundry, Lawrence Berkeley National Laboratory; Department of Physics, University of California-Berkeley, University of California, Berkeley and Lawrence Berkeley National Lab, Molecular Foundry, Lawrence Berkeley National Laboratory, and Department of Physics, UC-Berkeley, Lawrence Berkeley National Laboratory