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Abstract: The electronic states of sodium ion (Na+) trapped on the model surfaces of amorphous carbon have been investigated by means of hybrid density functional theory (DFT) calculations to elucidate the nature of interaction between Na+/Na and the amorphous carbon surfaces. Also, direct molecular orbital–molecular dynamics (MO–MD) calculation [Tachikawa and Shimizu, J. Phys. Chem. B, 110 (2006) 20445] was applied to diffusion processes of the Na+ ion on the model surface of amorphous carbon. Seven models of graphene sheets (n =7, 14, 19, 29, 37, 44 and 52, where n means numbers of rings in each carbon cluster) were considered in the present study. The B3LYP/LANL2MB calculations showed that the sodium ion is located at 2.24–2.26 Å from the graphene surfaces. The direct MO–MD calculations showed that the Na+ ion diffuses freely on the surface above 300 K. At higher temperature (1100 K), the Na+ ion moved from the center to edge region of the model surface. The nature of the interaction between Na+ and the amorphous carbon surfaces was discussed on the basis of theoretical results. [Copyright &y& Elsevier]

Abstract: Through-space electron transfer between the benzene rings of [3 n ]cyclophanes, n =2 – 5, was investigated using density functional theory calculations, CAM-B3LYP/6-311++G**. An external point charge, q, was placed on the axis perpendicular to a benzene ring of the cyclophane molecule. The dependence of the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap and bond overlap population (BOP) of cyclophanes on the values of q and n are discussed. The HOMO–LUMO gap generally decreases as q decreases and n increases. It is found from the BOP analysis that electron transfer occurs mainly through LUMO+2 for n =2, LUMO for n =3 and n =4, and LUMO+4 for n =5. The result that the values of the BOP for n =2 and 5 increase as q decreases means that the through-space electron transfer is enhanced by the negative charge on the neighboring molecule in the solid. [Copyright &y& Elsevier]