TY - JOUR
T1 - The Ag + state falls below 3Ag - at carotenoid-relevant conjugation lengths
AU - Taffet, Elliot J.
AU - Scholes, Gregory D.
N1 - Funding Information:
EJT would like to thank Professor Garnet Chan, Dr. Qiming Sun and Sheng Guo for fruitful discussions regarding DMRG and for mentorship in the implementation of DMRG-NEVPT2 calculations using PySCF interfaced with Block . This work was supported by Princeton University through the Innovation Fund for New Ideas in the Natural Sciences.
Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2018/11/14
Y1 - 2018/11/14
N2 - Spectroscopy of all-trans linear polyenes is characterized by a one-photon electronic transition to a bright S2 state and two-photon transition to a lower-lying dark S1 state. We apply ab initio quantum chemistry to distinguish additional diffuse dark singlet states. Building on a systematic implementation of CASSCF and DMRGSCF coupled to strongly-contracted NEVPT2, we report the excitation energies for a series of polyenes from butadiene to C16H18 at optimized S0, S1 and S2 geometries. Ionic/covalent state inversion within each manifold is identified at seven conjugated double bonds, making the Bu - a dark intermediate state at its optimized geometry and the Ag + the S3 state at the S0 optimized geometry. The relevance of these results to the function of carotenoids in photosynthetic light harvesting is discussed.
AB - Spectroscopy of all-trans linear polyenes is characterized by a one-photon electronic transition to a bright S2 state and two-photon transition to a lower-lying dark S1 state. We apply ab initio quantum chemistry to distinguish additional diffuse dark singlet states. Building on a systematic implementation of CASSCF and DMRGSCF coupled to strongly-contracted NEVPT2, we report the excitation energies for a series of polyenes from butadiene to C16H18 at optimized S0, S1 and S2 geometries. Ionic/covalent state inversion within each manifold is identified at seven conjugated double bonds, making the Bu - a dark intermediate state at its optimized geometry and the Ag + the S3 state at the S0 optimized geometry. The relevance of these results to the function of carotenoids in photosynthetic light harvesting is discussed.
KW - Ab initio quantum chemistry
KW - Complete active space
KW - Density Matrix Renormalization Group
KW - Multireference perturbation theory
KW - N-Electron Valence Perturbation Theory
KW - Static/dynamic correlation
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U2 - 10.1016/j.chemphys.2017.12.008
DO - 10.1016/j.chemphys.2017.12.008
M3 - Article
AN - SCOPUS:85042374828
SN - 0301-0104
VL - 515
SP - 757
EP - 767
JO - Chemical Physics
JF - Chemical Physics
ER -