A new lithium salt electride with an excess electron pair is designed, for the first time, by means of doping two sodium atoms into the lithium salt of pyridazine. For this series of electride molecules, the structures with all real frequencies and the static first hyperpolarizability (beta 0) are obtained at the second-order Møller-Plesset theory (MP2). Pyridazine H 4C 4N 2 becomes the lithium salt of pyridazine Li-H 3C 4N 2 as one H atom is substituted by Li. The lithium salt effect on hyperpolarizability is observed as the beta 0 value is increased by about 170 times from 5 to 859 au. For the electride effect, an electride H 4C 4N 2...Na 2 formed by doping two Na atoms into pyridazine, the beta 0 value is increased by about 3000 times from 5 to 1.5 x 10 (4) au. Furthermore, combining these two effects, that is, lithium salt effect and electride effect, more significant increase in beta 0 is expected. A new lithium salt electride Li-H 3C 4N 2...Na 2 is thus designed by doping two Na atoms into Li-H 3C 4N 2. It is found that the new lithium salt electride, Li-H 3C 4N 2...Na 2, has a very large beta 0 value (1.412 x 10 (6) au). The beta 0 value is 2.8 x 10 (5) times larger than that of H 4C 4N 2, 1644 times larger than that of Li-H 3C 4N 2, and still 93 times larger than that of the electride H 4C 4N 2...Na 2. This extraordinary beta 0 value is a new record and comes from its small transition energy and large difference in the dipole moments between the ground state and the excited state. The frequency-dependent beta is also obtained, and it shows almost the same trends as H 4C 4N 2 << Li-H 3C 4N 2 << H 4C 4N 2...Na 2 << Li-H 3C 4N 2...Na 2. This work proposes a new idea to design potential candidate molecules with high-performance NLO properties.

Classical molecular dynamics simulations have been used to investigate the absorption and diffusion behavior of polyethylene (PE) chains on the surface of the side-wall of the carbon nanotube (CNT). Different degrees of polymerization from 50 to 80 at separate temperatures of 300, 400, 500, and 600 K are considered. Through the simulation, it is examined that the PE chains are absorbed on the surface of CNT and form stable composites with the nanotube as capsules. It is found that the most probable distance between the CNT and the C atoms in backbone of PE molecules only attribute to the temperature, and at T ¼ 300 K, this distance is about 3.8 Å . Furthermore, the pattern of the composites mainly depends on the temperature and the length matching of the chains and the CNT. In particular, the PE chains keep approximately linear conformation, and extend along the axis of the CNT at the room temperature. V V C 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 272-280, 2008

ABSTRACT:The structural properties of neutral and ionic Al n O 2 (n ϭ 1-10) clusters have been systematically investigated using the density functional method B3LYP with a standard 6-311ϩG(d) basis set. The calculated results show that in the Al n O 2 ϩ , Al n O 2 , and Al n O 2 Ϫ (n Ն 3) clusters, O atoms tend to penetrate into the aluminum clusters with some Al atoms moving outward. The binding energies and natural charges populations indicate that the oxygen-etching is generally stronger in the order Al n ϩ Ͻ Al n Ͻ Al n Ϫ for n Ͻ 3, and Al n ϩ Ͼ Al n Ͼ Al n Ϫ for n Ն 3. To further understand the mechanism of interaction between Al and O 2 , the adsorption of O 2 on the Al(111) surface was studied using the density functional theory with plane wave pseudopotential method. The calculated results are consistent with the experimental observation that the O 2 molecule would dissociate on the Al(111) surface and be adsorbed in adjacent hollow sites, forming a local structure of Al 3 O-Al 3 O.