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The energy dissipated by a moving charge approaching a metal has been obtained for a wide range of the incoming velocities. Regime limits for very small or very great velocities are analysed as particular cases, and some experimental evidence for the system He+/Au is discussed in the light of our results. 相似文献
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Summary The static response to a charge impurity near a metal surface is computed in the RPA approximation for the case of a finite
barrier. Particular attention is given to the problem of the correct infinite-volume limit and to the contribution of the
one-particle states with energy higher than the potential barrier, which has been found to be not negligible. An integral
equation for the self-consistent potential is derived and solved numerically. Results for Na and Zn are exhibited, showing
remarkable difference with respect to the infinite-barrier case.
Riassunto La risposta statica ad un'impurezza di carica in prossimità della superficie di un metallo è calcolata nell'approssimazione delle fasi a caso (RPA) nel caso di una barriera finita. Sono trattati con particolare cura i problemi del corretto limite di volume infinito e del contributo degli stati ad una particella con energia superiore alla barriera di potenziale, contributo che risulta non trascurabile. Si deriva e risolve numericamente un'equazione integrale per il potenziale autoconsistente. Sono presentati i risultati per Na e Zn, da cui si può rilevare una notevole differenza rispetto al caso della barriera infinita.
Резюме В случае конечного барьера в приближении случайных фаз вычисляется статический отклик на заряженную примесь вблизи металлической поверхности. Особое внимание уделяется проблеме корректного предела бесконечного объема и вкладу одно-частичных состояний с энергией выше потенциального барьера, который, как получено, не является пренебрежимо малым. Выводится интегральное уравнение для самосогласованного потенциала и решается численно. Полученные результаы для Na и Zn обнаруживают значительное различие с результатами для случая бесконечного барьера.相似文献
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《Physics letters. A》1972,38(4):255-256
The screening of an external electric field and the distribution of excess charge near a metal surface have been determined self-consistently for the jellium model. 相似文献
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The canonical density matrix for a non-interacting electron gas bounded by a planar infinite barrier is calculated exactly by solving the Bloch equation for free particles. A closed expression describing the shape and size of the Fermi hole is thereby obtained. 相似文献
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The force on an ion located near a condensed-matter surface determines its Brownian motion along the surface. We have studied the dissipative component of this force using a model in which the ion interacts with a metal while moving parallel with its surface. We recover the known asymptotic form of the force for large separations when only electron-hole excitations are accounted for but find a different form when damping of collective states is included. 相似文献
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The lowest electronic excitations of benzene and a set of donor-acceptor molecular complexes are calculated for the gas phase and on the Al(111) surface using the many-body Bethe-Salpeter equation. The energy of the charge-transfer excitations obtained for the gas phase complexes are found to be around 10% lower than the experimental values. When the molecules are placed outside the surface, the enhanced screening from the metal reduces the exciton binding energies by several eVs and the transition energies by up to 1 eV depending on the size of the transition-generated dipole. As a striking consequence we find that close to the metal surface the optical gap of benzene can exceed its quasiparticle gap. A classical image charge model for the screened Coulomb interaction can account for all these effects which, on the other hand, are completely missed by standard time-dependent density functional theory. 相似文献
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The long range electromagnetic interactions between a spherical atom and a metal surface affects the non-linear response properties of the spherical system. As an example it is shown that, even in the absence of any electron overlap, a physisorbed atom acquires a non-zero second order non-linear polarizability tensor. Numerical estimations of this effect are performed for various atom-metal systems. 相似文献
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We present a discussion on the absorptance of electromagnetic radiation per unit length in the surface region of a free electron like metal. We wish particularly to comment on recent work by Feibelman, Kliewer, Forstmann and Stenscke, who all considered different approximations of the jellium model. We are using a unified treatment from which the results in their models can easily be obtained. Our results confirm the general conclusions by Kliewer about a strong coupling to the electron-hole excitations which lead to a locally negative absorptance. In the model considered by Feibelman there is no such coupling to electron-hole excitations and he obtains the classical results for the absorptance. Forstmann and Stenschke have recently applied a hydrodynamical approach which gives results in disagreement with Kliewer's theory as well as with our own results, and we make some comments about their approach. 相似文献
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Smith-Purcell radiation from a charge running near a photonic crystal is calculated for a slab system of a periodic array of dielectric spheres, with the photonic band effect taken into account exactly. The radiation spectrum has a series of resonantly enhanced structures, which are shown to arise accompanying the excitation of the photonic bands. It is also shown that the overall intensity of the emission band does not depend very strongly on the slab thickness but the height of the resonant peaks increases progressively with thickness due to the enhanced Q value of excited photonic bands. 相似文献
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W.L. Schaich 《Solid State Communications》1974,15(2):357-360
We derive and evaluate a pertubative expression for the friction parameter of a Brownian motion formalism. Our model system consists of a single massive ion near the surface of an electron gas. The relation of this friction parameter to recently calculated dynamical corrections to the image potential is clarified. 相似文献
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GE Meihua ZHANG Yanhui WANG Dehua DU Mengli & LIN Shenglu . College of Physics Electronics Shandong Normal University Jinan China . Department of Mathematics Physics Shandong Institute of Architecture Engineering Jinan China . Institute of Theoretical Physics Chinese Academy of Sciences Beijing China 《中国科学G辑(英文版)》2005,48(6):667-675
In recent years much attention is focused on the dynamics of Rydberg atom in exter- nal fields. At the same time Rydberg atom near a metal surface plays an important role as a typical theoretical model and produces measurable experimental response[1]. As an interesting model it covers many dynamical effects: instantaneous van der Waals inter- action[2,3], Zeeman-Stark effects and diamagnetic effects in strong fields[4], and so on. Its classical motion is very complex. When the atom-surface i… 相似文献
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Using the first-order density matrix of an infinite barrier model of a metal surface, the exchange energy density can be evaluated exactly as a function of the distance z from the barrier. This result is compared with the local approximation where the electron density in the model. The local approximation follows the exact result quite closely at all z but leads to a large percentual error in the integrated surface exchange energy. 相似文献
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The dynamical properties of Rydberg hydrogen atom near a metal surface are presented by using the methods of phase space analysis
and closed orbit theory. Transforming the coordinates of the Hamiltonian, we find that the phase space of the system is divided
into vibrational and rotational region. Both the Poincaré surface of section and the closed orbit theory verify the same conclusion
clearly. In this paper we choose the atomic principal quantum number asn=20. The dynamical character of the exited hydrogen atom depends sensitively on the atom-surface distanced. Whend is sufficiently large, the atom-surface potential can be expressed by the traditional van der Waals force and the system
is integrable. Whend becomes smaller, there exists a critical valued
c. Ford>d
c, the system is near-integrable and the motion is regular. While chaotic motion appears ford<d
c, and the system tends to be non-integrable. The trajectories become unstable and the electron might be captured onto the
metal surface. 相似文献
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A. N. Zinov’ev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(5):758-759
When an ion approaches a metal surface, an induced charge forms in it, which affects the formation of electronic states in an ion-metal system. The spatial distribution of the electron density near the metal surface has been calculated in the case of the classical consideration and in the framework of the energy density functional approximation. It is shown that the space cloud exists in the form of a sphere segment; in this case, this cloud is shifted toward the approaching ion in the quantum-mechanical consideration. 相似文献