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Abstract: The electronic transport properties of the molecular device based on double‐cage fluorinated fullerene C20F18(NH)2C20F18 were studied theoretically. The results show that the device exhibits two negative differential resistance (NDR) peaks in its I‐V curve. The NDR peak under low bias voltage originates from the bias‐induced alignment of the molecular orbitals, and the conduction channel being suppressed at a certain bias voltage is the main reason for the NDR peak under a relatively high bias voltage. [ABSTRACT FROM AUTHOR]

The geometrical structures, energetics properties, and aromaticity of C 36-nSi n ( n ≤ 18) fullerene-based clusters were studied using density functional theory calculations. The geometries of C 36-nSi n clusters undergo strong structural deformation with the increase of Si substitution. For the most energy favorable structures of C 36-nSi n, the silicon and carbon atoms form two distinct homogeneous segregations. Subsequently, the binding energy, HOMO–LUMO energy gap, vertical ionization potential, vertical electron affinity, and chemical hardness for the energetic favorable C 36-nSi n geometries were computed and analyzed. In addition, the aromatic property of C 36-nSi n cagelike clusters was investigated, and the result demonstrate that these C 36-nSi n cagelike structures possess strong aromaticity. [ABSTRACT FROM AUTHOR]

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ABSTRACT: Stability and electronic property calculations are performed systematically based on density functional theory at the B3LYP/6-31G(d) level for Td C28 fullerene and exohedral fluorine and trifluoromethyl derivatives C28F4–n(CF3)n (n = 0,1,2,3,4). All the exohedral derivatives that are on the potential energy surfaces are kinetically stable with large HOMO-LUMO gaps. Further investigations show that binding energies of C28F4–n(CF3)n (n = 0,1,2,3,4) molecules are positive, suggesting they are thermodynamically stable. An analysis of the π-orbital axis vector indicates the high strain in Td C28 cage could be greatly released by fluorine and trifluoromethyl decorations. Mulliken charge analysis reveals that adding different electron groups to the Td C28 cage can cause remarkably different charge populations. In addition, from the ionization potential and electron affinity investigations, the C28F4–n(CF3)n (n = 0,1,2,3,4) molecules manifest weak redox properties. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [ABSTRACT FROM AUTHOR]

The potential energy surface information of the CH2CO + CN reaction is obtained at the B3LYP/6-311+G(d,p) level. To gain further mechanistic knowledge, higher-level single-point calculations for the stationary points are performed at the QCISD(T)/6-311++G(d,p) level. The CH2CO + CN reaction proceeds through four possible mechanisms: direct hydrogen abstraction, olefinic carbon addition–elimination, carbonyl carbon addition–elimination, and side oxygen addition–elimination. Our calculations demonstrate that R→IM1→TS3→P3: CH2CN + CO is the energetically favorable channel; however, channel R→IM2→TS4→P4: CH2NC + CO is considerably competitive, especially as the temperature increases (R, IM, TS, and P represent reactant, intermediate, transition state, and product, respectively). The present study may be helpful in probing the mechanism of the CH2CO + CN reaction. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [ABSTRACT FROM AUTHOR]

Abstract: A systematic study on the geometrical structures and electronic properties of C68X4 (X=H, F, and Cl) fullerene compounds has been carried out on the basis of density functional theory. In all classical C68X4 isomers with two adjacent pentagons and one quasifullerene isomer [C s :C68(f)] containing a heptagon in the framework, the C s :0064 isomers are most favorable in energy. The addition reaction energies of C68X4 (C s :0064) are high exothermic, and C68F4 is more thermodynamically accessible. The C68X4 (C s :0064) possess strong aromatic character, with nucleus independent chemical shifts ranging from −22.0 to −26.1ppm. Further investigations on electronic properties indicate that C68F4 and C68Cl4 could be excellent electron-acceptors for potential photonic/photovoltaic applications in consequence of their large vertical electron affinities (3.29 and 3.15eV, respectively). The Mulliken charge populations and partial density of states are also calculated, which show that decorating C68 fullerene with various X atoms will cause remarkably different charge distributions in C68X4 (C s :0064) and affect their electronic properties distinctly. Finally, the infrared spectra of the most stable C68X4 (C s :0064) molecules are simulated to assist further experimental characterization. [Copyright &y& Elsevier]