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981.
The geometric and electronic structures of poly(9,9-dioctylfluorene) (PFO) oligomer interacting with Ca atoms were studied using M?ller-Plesset perturbation theory. A weak interaction with little charge transfer and with a relatively long Ca-C distance (about 4.0 Angstrom) was found when only one Ca atom was attached to a PFO unit. However, when two Ca atoms were adsorbed at a PFO unit, a strong interaction with a shorter Ca-C distance (about 2.67 Angstrom) took place with considerable charge transfer from the Ca atom to the PFO, resulting in significant deformation in the backbone of the PFO oligomer. In the latter case, the frontier orbitals of the PFO were modified. However, the deformed PFO and its modified frontier orbitals could be recovered when oxygen was added, which is in good agreement with experimental observation. 相似文献
982.
Temperature-dependent surface tension gamma(lv)(T) and its temperature coefficient (T) [=dgamma(lv)(T)/dT] for liquid metals are thermodynamically determined on the basis of an established model for surface energy of crystals. The model predictions correspond to the available experimental or theoretical results. It is found that for metallic liquids gamma(lv)(T(m)) proportional, variant H(v)/V(m)(2/3), gamma(lv)(T) proportional, variant T, and (T) proportional, variant T over a certain temperature range (including T < T(m) and T >/= T(m)), where H(v) and V(m) are the liquid-vapor transition enthalpy at boiling temperature T(b) and the atomic volume at melting temperature T(m), respectively. Furthermore, T(m)(T(m))/gamma(lv)(T(m)) almost remains constant, which gives a way to estimates of (T(m)) values when T(m) and gamma(lv)(T(m)) are known. 相似文献
983.
Tian CS Qian D Wu D He RH Wu YZ Tang WX Yin LF Shi YS Dong GS Jin XF Jiang XM Liu FQ Qian HJ Sun K Wang LM Rossi G Qiu ZQ Shi J 《Physical review letters》2005,94(13):137210
The body-centered-cubic (bcc) phase of Ni, which does not exist in nature, has been achieved as a thin film on GaAs(001) at 170 K via molecular beam epitaxy. The bcc Ni is ferromagnetic with a Curie temperature of 456 K and possesses a magnetic moment of 0.52+/-0.08 micro(B)/atom. The cubic magnetocrystalline anisotropy of bcc Ni is determined to be +4.0x10(5) ergs x cm(-3), as opposed to -5.7x10(4) ergs x cm(-3) for the naturally occurring face-centered-cubic (fcc) Ni. This sharp contrast in the magnetic anisotropy is attributed to the different electronic band structures between bcc Ni and fcc Ni, which are determined using angle-resolved photoemission with synchrotron radiation. 相似文献
984.
Ohta T Schmidt DA Meng S Klust A Bostwick A Yu Q Olmstead MA Ohuchi FS 《Physical review letters》2005,94(11):116102
A highly anisotropic growth morphology is found for heteroepitaxial gallium sesquiselenide (Ga2Se3) on the lattice matched substrate, arsenic-terminated Si(001). Scanning tunneling microscopy of Ga2Se3 films reveals nanoscale, wirelike structures covering the surface in parallel lines, less than 1 nm wide and up to 30 nm long. Core-level photoemission spectroscopy and diffraction reveals the local structure of buried Ga and Se atoms to reflect the bulk, defected zinc-blende structure of beta-Ga2Se3, which contains ordered 110 arrays of Ga vacancies. These ordered vacancy lines are proposed to be responsible for the observed growth anisotropy in heteroepitaxial Ga2Se3. 相似文献
985.
Primal-Dual Interior-Point Algorithms for Semidefinite Optimization Based on a Simple Kernel Function 总被引:3,自引:0,他引:3
G.?Q.?Wang Y.?Q.?BaiEmail author C.?Roos 《Journal of Mathematical Modelling and Algorithms》2005,4(4):409-433
Interior-point methods (IPMs) for semidefinite optimization (SDO) have been studied intensively, due to their polynomial complexity
and practical efficiency. Recently, J. Peng et al. introduced so-called self-regular kernel (and barrier) functions and designed
primal-dual interior-point algorithms based on self-regular proximities for linear optimization (LO) problems. They also extended
the approach for LO to SDO. In this paper we present a primal-dual interior-point algorithm for SDO problems based on a simple
kernel function which was first presented at the Proceedings of Industrial Symposium and Optimization Day, Australia, November 2002; the function is not self-regular. We derive the complexity analysis for algorithms based on this
kernel function, both with large- and small-updates. The complexity bounds are
and
, respectively, which are as good as those in the linear case.
Mathematics Subject Classifications (2000) 90C22, 90C31. 相似文献
986.
Cai YQ Mao HK Chow PC Tse JS Ma Y Patchkovskii S Shu JF Struzhkin V Hemley RJ Ishii H Chen CC Jarrige I Chen CT Shieh SR Huang EP Kao CC 《Physical review letters》2005,94(2):025502
The near K-edge structure of oxygen in liquid water and ices III, II, and IX at 0.25 GPa and several low temperatures down to 4 K has been studied using inelastic x-ray scattering at 9884.7 eV with a total energy resolution of 305 and 175 meV. A marked decrease of the preedge intensity from the liquid phase and ice III to ices II and IX is attributed to ordering of the hydrogen bonds in the proton-ordered lattice of the latter phases. Density functional theory calculations including the influence of the Madelung potential of the ice IX crystal correctly account for the remaining preedge feature. Furthermore, we obtain spectroscopic evidence suggesting a possible new phase of ice at temperatures between 4 and 50 K. 相似文献
987.
988.
Li L Schülzgen A Temyanko VL Qiu T Morrell MM Wang Q Mafi A Moloney JV Peyghambarian N 《Optics letters》2005,30(10):1141-1143
We report fabrication and testing of the first phosphate glass microstructured fiber lasers with large Er-Yb-codoped cores. For an 11-cm-long cladding-pumped fiber laser, more than 3 W of continuous wave output power is demonstrated, and near single-mode beam quality is obtained for an active core area larger than 400 microm2. 相似文献
989.
Triple-layer omnidirectional reflectors (ODRs) consisting of a semiconductor, a quarter-wavelength transparent dielectric layer, and a metal have high reflectivities for all angles of incidence. Internal ODRs (ambient material's refractive index n > 1.0) are demonstrated that incorporate nanoporous SiO2, a low-refractive-index material (n = 1.23), as well as dense SiO2 (n = 1.46). GaP and Ag serve as the semiconductor and the metal layer, respectively. Reflectivity measurements, including angular dependence, are presented. Calculated angle-integrated TE and TM reflectivities for ODRs employing nanoporous SiO2 are R(int)/TE = 99.9% and R(int)/TM = 98.9%, respectively, indicating the high potential of the ODRs for low-loss waveguide structures. 相似文献
990.
The traditional diffusion theory, often used for isotropic sources, becomes inaccurate at short source-detector spacings and cannot be applied to media with large absorption or with small scattering strengths. We show that for any type of source anisotropy, a Green's-function-based procedure can remove these limitations. The accuracy of the new approach is examined through a comparison with the numerical solution to the radiative transfer equation. 相似文献