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171.
Ding Changgeng Yang Jinlong Cui Xiangyuan Wang Kelin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(1):123-126
Geometrical and electronic structures of C35X fullerenes with , N and Si as substitutional dopants have been studied. Three non-equivalent sites in the D6h structure of C36 have been considered for the substitution. We have found that the dopant has a strong tendency to substitute at sites where
the carbon atom contributes significantly to the frontier orbitals of C36 and has the weakest interaction with its nearest-neighbor atoms. The relative stability of C35Si and C35B (C35N) has been investigated and high chemical reactivity of C35Si has been predicted.
Received 8 July 1999 and Received in final form 4 October 1999 相似文献
172.
R. Plaga 《Foundations of Physics Letters》2000,13(5):461-476
Karl Popper proposed a way to test whether a proposed relation of a quantum-mechanical state to perceived reality in the Copenhagen interpretation (CI) of quantum mechanics—namely that the state of a particle is merely an expression of what is known about the system—is in agreement with all experimental facts. A conceptual flaw in Popper's proposal is identified and an improved version of his experiment (called Extension step 1)—which fully serves its original purpose—is suggested. The main purpose of this paper is to suggest to perform this experiment. The results of this experiment predicted under the alternative assumptions that the CI or the many-worlds interpretation (MWI) is correct are shown to be identical. Only after a further modification (called Extension step 2) (the use of an ion isolated from the macroscopic environment as particle detector) the predictions using the respective interpretations become qualitatively different. This is because what is known by a human observer H can fail as a basis for the prediction of the statistical distribution of measurement results within the MWI in special cases: The temporal evolution of a system un-entangled with H (like the isolated ion) can depend on another system's state components that are entangled with states ortogonal to H. Thus—within the CI—for H they are known not to exist. Yet H can infer their existence by studying the evolution of the ion. 相似文献
173.
In an earlier paper dealing with the flat-topped light beams [Y. Li, Opt. Lett. 27 (2002) 1007], it is shown that the flat-topped beams can be expressed as 1 − [1 − exp(−ξ2)]M, where ξ is a dimensionless parameter and M is a non-negative number. The binomial expansion of this express contains only lowest-order Gaussian modes; this situation makes it possible to develop a new formulation of diffraction of converging spherical wave at an aperture in a plane opaque screen if the Gaussian mode expansion is employed to describe the boundary values of the screen. 相似文献
174.
We discuss transformation laws of electric and magnetic fields under Lorentz transformations, deduced from the classical field
theory. It is found that we can connect the resulting expression for a bivector formed with those fields, with the expression
deduced from the Wigner transformation rules for spin-1 functions of massive particles. This mass parameter should be interpreted because the constancy of speed of light forbids the existence of the
photon mass. 相似文献
175.
We present new results on the correspondence between symmetries, conservation laws and variational principles for field equations in general non-abelian gauge theories. Our main result states that second order field equations possessing translational and gauge symmetries and the corresponding conservation laws are always derivable from a variational principle. We also show by the way of examples that the above result fails in general for third order field equations. 相似文献
176.
Edyta Podstawka Pawe Kafarski Leonard M. Proniewicz 《Journal of Raman spectroscopy : JRS》2008,39(12):1726-1739
A comparative study of molecular structures of five L ‐proline (L ‐Pro) phosphonodipeptides: L ‐Pro‐NH‐C(Me,Me)‐PO3H2 (P1), L ‐Pro‐NH‐C(Me,iPr)‐PO3H2 (P2), L ‐Pro‐L ‐NH‐CH(iBu)‐PO3H2 (P3), L ‐Pro‐L ‐NH‐CH(PA)‐PO3H2 (P4) and L ‐Pro‐L ‐NH‐CH(BA)‐PO3H2 (P5) has been carried out using Raman and absorption infrared techniques of molecular spectroscopy. The interpretation of the obtained spectra has been supported by density functional theory calculations (DFT) at the B3LYP; 6–31 + + G** level using Gaussian 2003 software. The surface‐enhanced Raman scattering (SERS) on Ag‐sol in aqueous solutions of these phosphonopeptides has also been investigated. The surface geometry of these molecules on a silver colloidal surface has been determined by observing the position and relative intensity changes of the Pro ring, amide, phosphonate and so‐called spacer (−R) groups vibrations of the enhanced bands in their SERS spectra. Results show that P4 and P5 adsorb onto the silver as anionic molecules mainly via the amide bond (∼1630, ∼1533, ∼1248, ∼800 and ∼565 cm−1), Pro ring (∼956, ∼907 and ∼876 cm−1) and carboxylate group (∼1395 and ∼909 cm−1). Coadsorption of the imine nitrogen atom and PO group with the silver surface, possibly by formation of a weaker interaction with the metal, is also suggested by the enhancement of the bands at 1158 and 1248 cm−1. P1, P2 and P3 show two orientations of their main chain on the silver surface resulting from different interactions of the C CH3, NH and CONH fragments with this surface. Bonding to the Ag surface occurs mainly through the imino atom (1166 cm−1) for P2, while for P1 and P3 it occurs via the methyl group(s) (1194–1208 cm−1). The amide group functionality (CONH) is practically not involved in the adsorption process for P1 and P2, whereas the Cs P bonds do assist in the adsorption. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
177.
Low-lying equilibrium geometric structures of Phosphorus-doped aluminum cluster Al
n
P (n = 2–12) clusters obtained by an all-electron linear combination of atomic orbital approach, within spin-polarized density
functional theory, are reported. The binding energy, dissociation energy, and stability of these clusters are studied within
the local spin density approximation (LSDA) and the three-parameter hybrid generalized gradient approximation (GGA) due to
Becke-Lee-Yang-Parr (B3LYP). Ionization potentials, electron affinities, hardness, and static polarizabilities are calculated
for the ground-state structures within the GGA. It is observed that symmetric structures with the P atom occupying a peripheral
position are lowest-energy geometries of Al
n
P (n = 2, 4–11), while the P impurities of Al3P and Al12P prefer to occupy internal sites in the aluminum clusters. Generalized gradient approximation extends bond lengths as compared
to the LSDA lengths. The odd-even oscillations in the dissociation energy, the second differences in energy, the HOMO–LUMO
gaps, the ionization potential, the electron affinity, and the hardness are more pronounced within both GGA and LSDA. The
stability analysis based on the energies clearly shows the clusters with an even number of valence electrons are more stable
than clusters with odd number of valence electrons. 相似文献
178.
ZHANG Da-Jun WU Hua DENG Shu-Fang BI Jin-Bo 《理论物理通讯》2008,49(6):1393-1396
Some general formulas in the Sato theory related to the nonisospectral KP and mKP hierarchies are derived for simplifying calculations. 相似文献
179.
We have theoretically investigated the atomic structure, magnetic behaviour, and electronic properties of Mn adsorbates on hydrogen passivated self-organised Bi nanolines on the Si(0 0 1)surface. It is found that the most stable geometry for monolayer (ML) coverage of Mn is just underneath the first Si(0 0 1) surface layer. The Mn atoms in the optimised configuration are seven-fold coordinated with their neighbouring Si atoms. Total energy calculations suggest that the Mn adsorbates form a degenerate state of ferromagnetic and anti-ferromagnetic lines parallel and adjacent to the self-assembled Bi lines. The density functional band structure calculation within the local-spin density approximation shows that the ferromagnetic system behaves like a metal in both spin channels. On the other side, the anti-ferromagnetic phase exhibits a half-metallic phenomenon with semiconducting character for the majority spin channel and semi-metallic character for the minority spin channel. 相似文献
180.
Rodrigo Vargas 《Journal of statistical physics》2008,133(3):491-511
We establish the existence of two weak coupling regime effective dynamics for an open quantum system of repeated interactions
(vanishing strength and individual interaction duration, respectively). This generalizes known results (Attal and Joye in
J. Stat. Phys. 126:1241–1283, 2007) in that the von Neumann algebras describing the system and the chain element may not be of finite type. Then (but now assuming
that the small system is of finite type), we prove that both effective dynamics capture the long-term behavior of the system:
existence of a unique asymptotic state for them implies the same property for the respective exact dynamics—provided that
the perturbation parameter is sufficiently small. The zero-th order term in a power series expansion in the perturbation parameter
of such an asymptotic state is given by the asymptotic state of the effective dynamics. We conclude by working out the case
in which the small system and the chain element are spins.
Dedicated to Mariana Huerta.
This work was partially funded by Nucleus Millennium Information and Randomness P04-069-F. 相似文献