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1.
ABSTRACTCore–valence double-electron ionisation spectra of a few small molecules – carbon monoxide, ammonia, methyl fluoride and thiophene – are presented and analysed using the self-consistent field algorithm introduced by Hans Jørgen Jensen 30 years ago. It confirms the utility of this algorithm, frequently employed to obtain stable and sharp convergence of wave functions for the benefit of calculations of a great variety of molecular properties, thus also for optimisation of core–valence states and for the interpretation of the corresponding spectra. 相似文献
3.
Potential curves for the four Hund's case (a) basis electronic states ( 2Σ, 2Π g, 2Π u, and 2Σ +) correlating with the I( 2P u) + I ?( 1S g) dissociation limit have been calculated at the MRCISD level of theory using an all-electron double-zeta basis set augmented with an extensive set of polarization and diffuse functions complete through i angular momentum functions. Transition moments for the dipole allowed transitions between these states are determined as a function of internuclear separation. The four Hund's case (a) curves are used to determine the six Hund's case (c) potential curves which arise when spin-orbit coupling is considered. The rovibrational eigenvalues for each of these six states are determined numerically, and standard spectroscopic constants are determined by fitting the energy of these levels to a Duham series. The results are compared with available experimental and theoretical information. 相似文献
4.
The electronic structures and optical properties of B3 ZnO series of
Zn electronic structures, optical properties, pseudopotential plane-wave method,
\\ \hspace*{1.9cm} p-type doping tendency,electronic structures, optical properties, pseudopotential plane-wave method,
\\ \hspace*{1.9cm} p-type doping tendencyProject supported by the National Natural Science
Foundation of China (Grant No~10625416).2007-04-252007-06-18The electronic structures and optical properties of B3 ZnO series of Zn4X4-yMy(X :O, S, Se or Te; M = N, Sb, C1 or I; y = 0 or 1) are studied by first-principles calculations using a pseudopotential plane-wave method. The results show that Zn d-X p orbital interactions play an important role in the p-type doping tendency in zinc-based Ⅱ-Ⅵ semiconductors. In ZnX, with increasing atomic number of X, Zn d-X p orbital interactions decrease and Zn s-X p orbital interactions increase. Additionally, substituting group-V elements for X will reduce the Zn d-X p orbital interactions while substituting group-VII elements for X will increase the Zn d-X p orbital interactions. The results also show that group-V-doped ZnX and group-Ⅷ-doped ZnX exhibit different optical behaviours due to their different orbital interaction effects. 相似文献
5.
The first electronic structural study of the complete valence shell binding energy spectra of the antimicrobial agent diacetyl, encompassing both the outer and inner valence regions, is reported. The binding energy spectra as well as the individual orbital momentum profiles have been measured by using a high resolution (e, 2e) electron momentum spectrometer (EMS) at an impact energy of 1200eV plus the binding energy, and using symmetric noncoplanar kinematics. The experimental orbital electron momentum profiles are compared with self-consistent field (SCF) theoretical profiles calculated using the Hartree-Fock approximation and Density Functional theory predictions in the target Kohn-Sham approximation which includes some treatment of correlation via the exchange and correlation potentials with a range of basis sets. The pole strengths of the main ionization peaks from the inner valence orbitals are estimated. 相似文献
6.
Electronic states of CF2Cl2 (dichlorodifluoromethane, Freon 12) have been studied using a new type of electron momentum spectrometer with a very high efficiency at an impact energy of 1200 eV plus binding energy. The experimental electron momentum profiles are compared with the density functional theory (DFT) and Hartree-Fock (HF) calculations. The relationship between orbital assignments in different coordinate systems is discussed. A new method of difference analysis based on the new type of electron momentum spectrometer is used to clarify the ambiguities regarding the orbital ordering. 相似文献
7.
We study the problem of separating the data produced by a given quantum measurement (on states from a memoryless source which is unknown except for its average state), described by a positive operator valued measure (POVM), into a meaningful ( intrinsic) and a not meaningful ( extrinsic) part. We are able to give an asymptotically tight separation of this form, with the intrinsic data quantified by the Holevo mutual information of a certain state ensemble associated to the POVM and the source, in a model that can be viewed as the asymptotic version of the convex decomposition of POVMs into extremal ones. This result is applied to a similar separation therorem for quantum instruments and quantum operations, in their Kraus form. Finally we comment on links to related subjects: we stress the difference between data and information (in particular by pointing out that information typically is strictly less than data), derive the Holevo bound from our main result, and look at its classical case: we show that this includes the solution to the problem of extrinsic/intrinsic data separation with a known source, then compare with the well–known notion of sufficient statistics. The result on decomposition of quantum operations is used to exhibit a new aspect of the concept of entropy exchange of an open dynamics. An appendix collects several estimates for mixed state fidelity and trace norm distance, that seem to be new, in particular a construction of canonical purification of mixed states that turns out to be valuable to analyze their fidelity. 相似文献
8.
The influence of short-range correlations in nuclei was investigated with realistic nuclear force. The nucleon-nucleon interaction was renormalized with Vlowk technique and applied to the Green’s function calculations. The Dyson equation was reformulated with algebraic diagrammatic constructions. We also analyzed the binding energy of 4He, calculated with chiral potential and CD-Bonn potential. The properties of Green’s function with realistic nuclear forces are also discussed. 相似文献
9.
The core and valence levels of β-PbO 2 have been studied using hard X-ray photoemission spectroscopy ( hν = 6000 eV and 7700 eV). The Pb 4f core levels display an asymmetric lineshape which may be fitted with components associated with screened and unscreened final states. It is found that intrinsic final state screening is suppressed in the near-surface region. A shift in the O 1s binding energy due to recoil effects is observed under excitation at 7700 eV. It is shown that conduction band states have substantial 6s character and are selectively enhanced in hard X-ray photoemission spectra. However, the maximum amplitude in the Pb 6s partial density of states is found at the bottom of the valence band and the associated photoemission peak shows the most pronounced enhancement in intensity at high photon energy. 相似文献
10.
In and out scalar vertex operators are constructed perturbatively in a class of recently discovered UV finite nonlinear -models describing the string evolution in gravitational plane wave backgrounds. They exhibit peculiar singularities in the target space related to the focusing phenomena in such backgrounds well known from the classical and quantum gravity theories. The computation is performed up to three loops of the usual perturbation expansion and to all loops of the weak field limit. An argument is given that the vertex operator singularities should persist, even when summing up the all perturbation expansions. 相似文献
11.
Electronic structure of free and neutral Rb and K clusters containing from few tens to few hundred atoms has been studied using synchrotron radiation. Core-level photoelectron spectroscopy has been used to probe the metallic nature of Rb and K clusters. We show that the metallicity exists down to the dimensions of few nanometers. Simultaneously the emergence and evolution of the valence band structure has been monitored by the valence-level photoelectron spectroscopy. 相似文献
12.
We have studied by absorption Mössbauer spectroscopy, some bridged derivatives of biferrocene, unoxidized (Fe II– Fe II) and mono-oxidized (Fe II – Fe III). The mixed-valence species exhibits a quasi-delocalized behavior at the Mössbauer timescale (~ 10 ?8 s), with a splitting of the lines which is interpreted in terms of a partial valence trapping. This in turn reveals intramolecular properties at variance from those of the unbridged cation. SCC-X α MO calculations have been performed; they correctly reproduce the measured quadruple splittings and provide evidence that the HOMO of the mixed-valence complex is of \(d_{xy} ,d_{x^2 - y^2 } \) type. Some consequences on the mixed-valence properties are discussed. 相似文献
13.
We have devised a thermodynamic model of cortical neurodynamics expressed at the classical level by neural networks and at the quantum level by dissipative quantum field theory. Our model is based on features in the spatial images of cortical activity newly revealed by high-density electrode arrays. We have incorporated the mechanism and necessity for so-called dark energy in knowledge retrieval. We have extended the model first using the Carnot cycle to define our measures for energy, entropy and temperature, and then using the Rankine cycle to incorporate criticality and phase transitions. We describe the dynamics of two interactive fields of neural activity that express knowledge, one at high and the other at low energy density, and the two operators that create and annihilate the fields. We postulate that the extremely high density of energy sequestered briefly in cortical activity patterns can account for the vividness, richness of associations, and emotional intensity of memories recalled by stimuli. 相似文献
14.
In this paper we have studied the mechanisms of so-called ‘indentation creep’ in a zirconium alloy. Nanoindentation was used to obtain strain rate data as the sample was indented at room temperature, at a homologous temperature below that for which creep behaviour would be expected for this material. A high value of strain rate was obtained, consistent with previous work on indentation creep. In order to elucidate the mechanism of time-dependent deformation, a load relaxation experiment was performed by uniaxial loading of a sample of the same alloy. By allowing relaxation of the sample from a peak load in the tensile test machine, a similar stress exponent was obtained to that seen in the nanoindentation creep test. We conclude that for metals, at temperatures below that at which conventional creep will occur, nanoindentation ‘creep’ proceeds through deformation on active slip systems that were initiated by prior loading beyond the plastic limit. It is therefore more appropriate to describe it as a viscoplastic process, and not as creep deformation. 相似文献
15.
We studied the behaviour under decoherence of four different measures of the distance between quantum states and classical states for the harmonic oscillator coupled to a linear Markovian bath. Three of these are relative measures, using different definitions of the distance between the given quantum states and the set of all classical states. The fourth measure is an absolute one, the negative volume of the Wigner function of the state. All four measures are found to agree, in general, with each other. When applied to the eigenstates | n〉, all four measures behave non-trivially as a function of time during dynamical decoherence. First, we find that the first set of classical states to which the set of eigenstate evolves is (by all measures used) closest to the initial set. That is, all the states decohere to classicality along the ‘shortest path’. Finding this closest classical set of states helps improve the behaviour of all the relative distance measures. Second, at each point in time before becoming classical, all measures have a state n? with maximal quantum-classical distance; the value n? decreases as a function of time. Finally, we explore the dynamics of these non-classicality measures for more general states. 相似文献
16.
The use of thin high-bandgap ‘spikes’ or thin low-bandgap ‘dips’ inside conventional rectangular quantum wells (QWs) gives supplementary flexibility in engineering intra- and inter-band energy level separation. The paper presents simulation and experimental studies on the effects of ‘spikes’ and ‘dips’ on the fundamental quantum well properties. 相似文献
17.
The interactions of solute atoms with vacancies play a key role in diffusion and precipitation of alloying elements,ultimately influencing the mechanical properties of aluminum alloys. In this study, first-principles calculations are systematically performed to quantify the solute–vacancy interactions for the 3 d–4 p series and the 4 d–5 p series. The solute–vacancy interaction gradually transforms from repulsion to attraction from left to right. The solute–vacancy binding energy is sensitive to the supercell size for elements at the beginning. These behaviors of the solute–vacancy binding energy can be understood in terms of the combination and competition between the elastic and electronic interactions. Overall, the electronic binding energy follows a similar trend to the total binding energy and plays a major role in the solute–vacancy interactions. 相似文献
18.
Core level photoemission with MgKα radiation ( hv = 1253.6 eV) and valence photoemission ( hv = 21.2 eV) are presented for Si(1 1 1)-Mo interfaces at various Mo coverages (up to 3.2·10 15 at cm −2) exposed to 6000 L of H 2O. The metal deposition strongly enhances the oxidation of Si with the complete H 2O dissociation and the formation of a SiO 2-like compound. The results are consistent with an interface growth with the formation of silicide islands. 相似文献
19.
Under the actions of different Hamiltonians on the different two-qubit input states by using the quantum Yang-Baxterization approach, we investigate the behaviors of the fidelity and the trace distance as measures of ‘closeness’ and distinguishability of two quantum states. The results show that the fidelity that is the main figure of merit for any communication and computing process can be kept to high values depending on the choice of the initial states and the Hamiltonians constructed by the Yang-Baxter equation. On the other hand, by choosing the initial states and Yang-Baxter systems which are the various extensions of the Yang-Baxter equations for several matrices, these quantifiers can be adjusted as desired to achieve many quantum computing and computational tasks. Furthermore, to quantify the performance of quantum teleportation we examine the teleportation fidelity for the outputs that correspond to the different two-qubit X-type states under the actions of the different Hamiltonians. It is possible to obtain high fidelity to use the quantum teleportation process. 相似文献
20.
We study the anisotropic electrostatic interaction with high rank multipoles (? = 5) for a set of 10 van der Waals complexes and 27 DNA base pairs. Multipoles are generated by the distributed multipole analysis (DMA) and by the topological quantum theory of ‘atoms in molecules’ (AIM). The convergence of the multipolar expansion of the interaction between topological atoms is improved by distributing the moments over extra off-nuclear sites via a shifting procedure. A clear theoretical distinction is made between partitioning and distributing. A substantial improvement in the convergence of the AIM multipole expansion is observed for the smaller van der Waals molecules. An AIM representation with extra sites on the bond midpoints performs as well as DMA with just nuclear sites. However, for the larger DNA base pairs no improvement follows from the introduction of extra sites with AIM. For these larger systems AIM and DMA expansions perform equivalently, provided that now DMA allows for extra sites. This work further encourages the development of a topological intermolecular force field. 相似文献
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