Quantum Size Effects in Excitations of Potassium Clusters

Felde, A. vom; Fink, J.; Ekardt, W.

doi:10.1103/physrevlett.61.2249

Cited by 35 publications

(34 citation statements)

References 17 publications

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“…(3), (5), (15), and (16)). At L ¼ 2L 0 ¼ 2a, which is assumed in what follows, the spectra of the plasmons of the considered planar model are almost identical to those of the spherical cluster with the radius a considered in the previous section, specifically, frequency (26) of the surface plasmon coincides precisely with the Mie frequency x p = ffiffi ffi 3 p…”

Section: Collisionless Damping: Plane-capacitor Modelmentioning

confidence: 96%

“…It can be found from general formula (15), when one takes into account that the wave number k p at this frequency is purely imaginary and equal to the inverse Debye length by the order of magnitude, i.e., k p ðx 0 Þ $ ik À1 D . In this case, the absolute value of the parameter k p ðx s Þa $ ia=k D is great by virtue of the condition a ) k D , and the left-hand side of Eq.…”

Section: Hydrodynamic Model (Approximation Of Weak Spatial Dispermentioning

confidence: 99%

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Resonances of surface and volume plasmons in atomic clusters

2011

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Section: Collisionless Damping: Plane-capacitor Modelmentioning

confidence: 96%

Section: Hydrodynamic Model (Approximation Of Weak Spatial Dispermentioning

confidence: 99%

Resonances of surface and volume plasmons in atomic clusters

2011

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“…13 It is expected that the wide-band-gap material MgO ͑7.8 eV͒ does not interact with the electronic structure of metal and semiconductor clusters. 14,7 It is also optically transparent in a large frequency band, which facilitates optical studies. Furthermore, the high melting point of MgO ͑3070 K͒ allows a study of phase transitions of nanoclusters.…”

Section: Introductionmentioning

confidence: 99%

Positron confinement in embedded lithium nanoclusters

et al. 2002

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Quantum confinement of positrons in nanoclusters offers the opportunity to obtain detailed information on the electronic structure of nanoclusters by application of positron annihilation spectroscopy techniques. In this work, positron confinement is investigated in lithium nanoclusters embedded in monocrystalline MgO. These nanoclusters were created by means of ion implantation and subsequent annealing. It was found from the results of Doppler broadening positron beam analysis that approximately 92% of the implanted positrons annihilate in lithium nanoclusters rather than in the embedding MgO, while the local fraction of lithium at the implantation depth is only 1.3 at. %. The results of two-dimensional angular correlation of annihilation radiation confirm the presence of crystalline bulk lithium. The confinement of positrons is ascribed to the difference in positron affinity between lithium and MgO. The nanocluster acts as a potential well for positrons, where the depth of the potential well is equal to the difference in the positron affinities of lithium and MgO. These affinities were calculated using the linear muffin-tin orbital atomic sphere approximation method. This yields a positronic potential step at the MgOʈLi interface of 1.8 eV using the generalized gradient approximation and 2.8 eV using the insulator model.

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“…Further, v(n(r, t)) is the potential energy density determined by exchange-correlation effects in the local density approximation [18], ni(r) is the ionic density in the jellium approximation, ~bk(r, t) is a single-particle wave function. Summation in (2) and (3) is performed over all occupied single-particle levels. The functional (1) includes the kinetic, exchange-correlation and Coulomb terms, respectively.…”

Section: Main Equations Of the Vpmmentioning

confidence: 99%

“…Experimental data clearly demonstrate a resonance structure of these oscillations [1][2][3][4][5][6][7][8][9][10]. Most of the experimental and theoretical investigations are devoted to the electric dipole (El) resonance.…”

Section: Introductionmentioning

confidence: 97%

CollectiveEλ excitations of surface character in spherical and deformed sodium clusters: vibrating potential model

Nesterenko

Kleinig

Гудков

1995

Z Phys D - Atoms, Molecules and Clusters

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Abstract. The self-consistent vibrating potential model (VPM) is extended for the description of E,~ surface collective excitations in alkali metal clusters with practically any kind of static deformation. The case of spherical clusters is also covered. Any single-particle potentials and valence electron densities for which the coefficients of the muttipole expansion are known can be used within the model. The strength function method incorporated into the model allows one to avoid solving the equations for every state and, as a result, simplifies the calculations drastically. The model is of a quite general character and can also be used for description of giant resonances in atomic nuclei if the Coulomb terms are neglected. The VPM is applied to calculate the El, E2 and E3 excitations in spherical (NAB, Na2o and Na40) and deformed (Nalo, Na18 and Na26) dusters. 71.45.-d; 36.40. + d PACS: I IntroductionCollective excitations (CE) associated with surface plasma oscillations are now a field of extensive investigation in alkali metal clusters (see, for example, recent papers [1-25] and references therein). Experimental data clearly demonstrate a resonance structure of these oscillations [1][2][3][4][5][6][7][8][9][10]. Most of the experimental and theoretical investigations are devoted to the electric dipole (El) resonance. Information about electric resonances of higher multipolarity is very scarce and limited mainly by theoretical estimations [18,22,24,26].Valence electrons in alkali clusters are often considered as moving in a mean field with shells like in atomic *On leave of absence from Technical University Dresden, Institute for Analysis, D-01062 Dresden, Germany **Department of Nuclear Physics, Charles University, V. Holesovichkach 2, CS-18000 Praha 8, Czech Republic nuclei [27,28]. Single-particle potential describing a mean field can be obtained in the self-consistent way [29,30] or approximated by some phenomenological potential [31][32][33][34][35]. Vibration of a mean field, which is described in terms of residual correlations, leads to collective E2 excitations. It is known that investigation of CE is rather complicated in clusters with open shells, which possess quandrupole (as well as hexadecapote and octupole) deformation [5-10, 31, 33-38]. In these clusters deformation splitting and Landau damping can lead to a quite complicated picture of CE when collective strength is distributed over many peaks. At the same time, investigation of CE in deformed clusters is very important: just a deformation splitting of the E1 resonance provides the most reliable information about the magnitude of cluster's deformation. To overcome these troubles, the random phase approximation (RPA) with separable residual forces is suitable. This approach provides the microscopic accuracy of numerical results without time consuming calculations. The self-consistent version of this approach, so called vibrating potential model (VPM) [18,39,40], is especially attractive. In the VPM, the form of residual forces and their str...

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Quantum Size Effects in Excitations of Potassium Clusters

Cited by 35 publications

References 17 publications

Resonances of surface and volume plasmons in atomic clusters

Resonances of surface and volume plasmons in atomic clusters

Positron confinement in embedded lithium nanoclusters

CollectiveEλ excitations of surface character in spherical and deformed sodium clusters: vibrating potential model

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