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Title: Role of Many-Body Effects in Describing Low-Lying Excited States of pi-Conjugated Chromophores: High-Level Equation-of-Motion Coupled-Cluster Studies of Fused Porphyrin Systems

Journal Article · · Journal of Chemical Theory and Computation, 7(7):2200-2208
DOI:https://doi.org/10.1021/ct200217y· OSTI ID:1022425

The unusual photophysical properties of the pi-conjugated chrompohores makes them potential building blocks of various molecular devices. In particular, significant narrowing of the HOMO-LUMO gaps can be observed as an effect of functionalization chromophores with polycyclic aromatic hydrocabrons (PAHs). In this paper we present equation-of-motion coupled cluster calculations for vertical excitation energies of several functionalized forms of porphyrins. The results of free-base porphyrin (FBP) clearly demonstrate significant differences between functionalization of FBP with one- (anthracene) and two-dimensional (coronene) structures. We also compare the EOMCC results with the experimentally available results for the anthracene fused zinc porphyrin. The impact of various-type correlation effects is illustrated on several benchmark models where the comparison with the experiment is possible. In particular, we demonstrate that for all excited states considered in this paper, all of them being dominated by single excitations, the inclusion of triply excited configurations is crucial for attaining qualitative agreement with the experiment. We also demonstrate the parallel performance of the most computationally intensive part of the completely renormalized EOMCCSD(T) approach (CR-EOMCCSD(T)) across 120,000 cores.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Organization:
USDOE Office of Science (SC)
DOE Contract Number:
AC05-76RL01830
OSTI ID:
1022425
Report Number(s):
PNNL-SA-78691; 44892; TRN: US201117%%856
Journal Information:
Journal of Chemical Theory and Computation, 7(7):2200-2208, Vol. 7, Issue 7
Country of Publication:
United States
Language:
English