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Möbius strip has attracted extensive interest due to its one-side structure, special physical and chemical properties. A new extended porphyrin with Möbius structure has been synthesized (Stępień et al., Angew. Chem. Int. Ed. 2007, 46, 7869). In this work, an electron is injected into Möbius to form Möbius anion. For Möbius, four methods (B3LYP, BHandHLYP, CAM-B3LYP, and LC-BLYP) obtain the similar first hyperpolarizability ( β0). However, for Möbius anion, four methods obtain very different β0 values (ranging from 9.85 × 103 to 8.33 × 105 au). Moreover, the β0 values of Möbius anion are larger than those of Möbius. Why? The considerable variation (ranging from 0.8162 to 1.7630) of spin contamination ( S2) of open-shell Möbius anion captures our attention. To probe the relationship between S2 and β0, the β0 values of Möbius anion were calculated using 23 methods. Interestingly, the Hartree-Fock (HF) composition increases from 0 to 50, the S2 value ranges from 0.7522 to 1.3372, and the β0 value increases from 4.3 × 103 to 7.36 × 104 au. Further, methods are 'dissected' to investigate the effect of HF composition on the S2. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

In this work, we add different strength of external electric field ( Eext) along molecule axis (Z-axis) to investigate the electric field induced effect on HArF structure. The H-Ar bond is the shortest at Eext = −189 × 10−4 and the Ar-F bond show shortest value at Eext = 185 × 10−4 au. Furthermore, the wiberg bond index analyses show that with the variation of HArF structure, the covalent bond H-Ar shows downtrend (ranging from0.79 to 0.69) and ionic bond Ar-F shows uptrend (ranging from 0.04 to 0.17). Interestingly, the natural bond orbital analyses show that the charges of F atom range from −0.961 to −0.771 and the charges of H atoms range from 0.402 to 0.246. Due to weakened charge transfer, the first hyperpolarizability (βtot) can be modulated from 4078 to 1087 au. On the other hand, make our results more useful to experimentalists, the frequency-dependent first hyperpolarizabilities were investigated by the coupled perturbed Hartree-Fork method. We hope that this work may offer a new idea for application of noble-gas hydrides. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Six N-substituted [ n]cyclacene ( n = 5, 6, 7,...,10) molecules were designed to study the relationship between the structure and first hyperpolarizability. Their static first hyperpolarizabilities ( β0) were obtained by MP2/6-31 + g(d) level. Two interesting relationships between the β0 value and the structure have been found: (1) The β0 value increases with the increase of the number n when n is odd: 3155 ([5]cyclacene) < 48,905 ([7]cyclacene) < < 393,444 ([9]cyclacene), and when n is even: 357,620 ([6]cyclacene) < 618,608 ([8]cyclacene) < 3,513,644 a.u. ([10]cyclacene). (2) The β0 values (in the range of 357,620 ~ 3,513,644 a.u.) of the N-substituted [ n]cyclacene (when n is odd) are much larger (in the range of 3155~393,444 a.u.) than that of the N-substituted [ n]cyclacene (when n is even). Furthermore, their frequency-dependent β (−2ω; ω, ω) and β (−ω; ω, 0) (ω = 0.005, 0.01, and 0.0239 a.u.) were also estimated by Møller-Plesset perturbation/6-31 + g(d) level. Among the frequency-dependent β (ω), [10]cyclacene has the largest β (−ω; ω, 0) and β (−2ω; ω, ω) to be 1.2 × 108 (ω = 0.01) and 2.9 × 107 a.u. (ω = 0.005 a.u.), which are much larger than the static β0 = 3.5 × 106 a.u. by 34 and 8 times. Our present work may offer a new idea in the design of high-performance tubiform nonlinear optical materials. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]