We investigate the static second hyperpolarizabilities (γ) of tetrathiafulvalene (TTF) and tetrathiapentalene (TTP) using the ab initio molecular orbital (MO) method. The cationic radical states of these systems (TTF+{radical dot} and TTP+{radical dot}) are expected to have large negative γ values, which are rare in organic systems, based on our classification rule of γ. It turns out that at the higher-order electron correlation level TTP+{radical dot} gives a large negative γ value though TTF+{radical dot} gives a positive γ. We also investigate the applicability of the density functional theory (DFT) methods to the calculation of the γ values for these systems. By tuning the mixing parameter of DFT/HF exchange term, a DFT method turns out to semiquantitatively reproduce the γ values of TTP and TTP+{radical dot} at the higher-order electron correlation method, i.e., CCSD(T), while fail in reproducing the γ value of TTF+{radical dot}. This suggests the necessity of further improvement in correlation functional for obtaining reliable γ values of charged radical states. © 2006 Elsevier B.V. All rights reserved.
CITATION STYLE
Yamada, S., Nakano, M., Kishi, R., Ohta, S., Takahashi, H., Furukawa, S. ichi, … Yamaguchi, K. (2006). Theoretical study on the second hyperpolarizabilities of tetrathiafulvalene (TTF) and tetrathiapentalene (TTP) using highly correlated ab initio MO and the density functional theory methods. Synthetic Metals, 156(5–6), 375–378. https://doi.org/10.1016/j.synthmet.2005.12.016
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