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4 páginas, 4 figuras., We investigate within a two-component jellium model the collective electronic excitations in a one-monolayer (1ML) potassium covered beryllium surface. The calculations of the surface dynamical response properties have been performed with one-particle energies and wave functions derived from the Kohn-Sham density-functional theory. The dispersion relation for the surface plasmon modes as well as the real and imaginary parts of the induced dynamical charge density oscillations are presented. Comparison of the collective modes in the 1ML K/Be system with that of a clean Be surface is made., We acknowledge partial support from the University of the Basque Country (Grant No. GIC07IT36607), the Departamento de Educación del Gobierno Vasco, and the Spanish Ministerio de Educación y Ciencia (Grant No. FIS200766711C0101).

The development of bulk metallic glasses as a prominent class of functional and structural materials has attracted considerable interest in the last years. One of the fundamental physical quantities necessary to describe the mechanical properties of the materials is the bulk modulus. In the present article, a simple method to estimate the bulk modulus and its pressure derivative is proposed. It is shown that these quantities can be estimated from the values of the constituent elements and their compositions. Comparison with measured data shows good agreement. The physical background of the method is discussed based on the jellium model of metals.

The fundamental issue in understanding the origin and growth mechanism of nanomaterials, from a fundamental unit is a big challenging problem to the scientists. Recently, an immense attention is generated to the researchers for prediction of exceptionally stable atomic cluster units as the building units for future smart materials. The present study is a systematic investigation on the stability and electronic properties of a series of bimetallic (semiconductor-alkaline earth) clusters, viz., BxMg3 (x=1-5) is performed, in search for exceptional and/ or unusual stable motifs. A very popular hybrid exchange-correlation functional, B3LYP along with a higher basis set, viz., 6-31+G[d,p] is employed for this purpose under the density functional formalism. The magic stability among the concerned clusters is explained using the jellium model. It is evident from the present study that the magic stability of B4Mg3 cluster arises due to the jellium shell closure., {"references":["A. Krüger, Carbon Materials and Nanotechnology, NY, USA: Wiley-\nVCH, 2010.","Handbook of nanotechnology (3rd Ed.), Ed. B. Bhushan (Springer-\nVerlag, NY, 2010).","Nanoclusters: A Bridge Across Disciplines, Eds. P. Jena, and A.W.\nCastleman, Jr. (Elsevier, Amsterdam, 2010).","R. Tenne, L. Margulis, M. Genut, G. Hodes, Nature (London) 360\n(1992) 444.","P. K. Chattaraj, and D. R. Roy, J. Phys. Chem. A 111 (2007) 4684.","D. R. Roy, J. Mol. Struct. 1007 (2012) 203.","H. W. Kroto, J. Heath, S. C. O'Brien, R. F. Curl, and R. E. Smalley,\nNature (London) 318 (1985) 162.","S. M. Gorun, Oxo Iron(III) aggregates, In: Metal clusters in proteins,\nEd. L. Que, Jr. (ACS symposium series, Washington, DC), vol. 372, p.\n196, 1988.","J. Bernholc, C. Roland, and B. I. Yakobson, Curr. Op. Sol. St. Mat. Sci.\n2 (1997) 706.\n[10] P. Martyniuk, and A. Rogalski, Prog. Quantum Electr. 32 (2008) 89.\n[11] L. Rapoport, Y. Bilik, Y. Feldman, M. Homyonfer, S. R. Cohen, and R.\nTenne, Nature (London) 387 (1997) 791. [12] S. M. Lee, Y. H. Lee, Y. G. Hwang, J. Elsner, D. Porezag, and T.\nFrauenheim, Phys. Rev. B 60 (1999) 7788.\n[13] R. I. G. Hughes, Science 14 (2006) 457.\n[14] P. Hohenberg, and W. Kohn, Phys. Rev. B 136 (1964) B864.\n[15] W. Kohn, and L. J. Sham, Phys. Rev. A 140 (1965) A1133.\n[16] R. G. Parr, and W. Yang, Density Functional Theory of Atoms and\nMolecules, New York, USA: Oxford University Press, 1989.\n[17] W. D. Knight, K. Clemenger, W. A. deHeer, W. A. Saunders, M. Y.\nChou, and M. L. Cohen, Phys. Rev. Lett. 52 (1984) 2141.\n[18] S. A. Claridge, A. W. Castleman Jr., S. N. Khanna, C. B. Murray, A.\nSen, and P. S. Weiss, ACS Nano 3 (2009) 244.\n[19] A. W. Castleman, Jr., and S. N. Khanna, J. Phys. Chem. C 113 (2009)\n2664.\n[20] D. R. Roy, J. Nano Res. 24 (2013) 77.\n[21] Quantum Phenomena in Clusters and Nanostructures, Eds. S. N.\nKhanna, and A. W. Castleman, Jr., New York, USA: Springer, 2003.\n[22] R. G. Pearson, Hard and Soft Acids and Bases, Stroudsberg, PA, USA:\nDowden, Hutchinson and Ross, 1973.\n[23] M. J. Frisch et. al., GAUSSIAN 09, Revision D.01; Gaussian, Inc.:\nPittsburgh PA, 2009.\n[24] A. D. Becke, J. Chem. Phys. 98 (1993) 5648.\n[25] V. A. Rassolov, M. A. Ratner, J. A. Pople, P. C. Redfern, and L. A.\nCurtiss, J. Comp. Chem. 22 (2001) 976.\n[26] CHEMCRAFT, G. A. Zhurko, and D. A. Zhurko\n(http://www.chemcraftprog.com).\n[27] I. Boustani, Phys. Rev. B 55 (1997) 16426.\n[28] A. F. Jalbout, J. Mol. Struct. (Theochem) 589–590 (2002) 75.\n[29] A. Lyalin, I. A. Solov'yov, A. V. Solov'yov, and W. Greiner, Phys. Rev.\nA 67 (2003) 063203.\n[30] K. P. Huber, and G. Herzberg, Molecular Spectra and Molecular\nStructure. IV. Constants of Diatomic Molecules, New York, USA: Van\nNostrand Reinhold, 1979."]}

Within an ab-initio DFT–LDA framework, we have investigated the polarization induced on He and Ne atoms by a jellium (Al-like) surface. It is shown that the displaced charge of the gas–metal system is spherically distributed around Ne. It is polarized instead for He with a dipole moment having the negative lobe towards the jellium surface. A relationship between the two different polarizations of He and Ne with corrugating and anti-corrugating behavior is discussed.

Due to the fundamental problems of energy source limitations and environmental pollution, hydrogen has become an attractive clean energy source for the future. Despite the fact that the incentive to switch to a hydrogen economy has increased, there are many problems which must be solved. One of the main unsolved issues is hydrogen storage. Among the potential materials to store hydrogen in a safe way, Mg has drawn interest owing to its high hydrogen capacity (7.6 wt%), light weight and low cost. In order to improve the hydrogen capacity of potential storage materials such as Mg, it is important to understand the site preferences of hydrogen atoms in the metal. Such behavior depends mainly on the screening charge density (Dn(r)) of the system proton-metallic host, from which all the physical macroscopic properties (viz. VH, DHS, B, etc.) and IDOS are determined. In the present work we study the interaction between a proton and Mg as host metal via ab initio calculations, using the Jellium model, based on the density-functional theory (DFT). The macroscopic properties are determined and compared with experimental results and values found in the bibliography. Furthermore, in order to obtain information about the electronic distribution of hydrogen and the nature of the Mg–H bonding, the IDOS is described.

Classically a nanowire with a length larger than its circumference is expected to be unstable due to Rayleigh instability that appears in specimens with large aspect ratio. In contrast we present experimental evidence that metallic nanowires with thicknesses ranging from one atom to hundreds of atoms present two series of exceptionally stable diameters, well determined and reproducible. The two series of stable diameters can be described in terms of shell closure effects. For low diameters the stability is given by the confinement of the electronic orbits in the nanowire cross-section, which is an electronic shell effect. Thicker nanowires are stable for densely packed structures, related to minima in the surface energy, which we refer to as atomic shell effect. A significant part of this thesis is dedicated to the study of shell effects for different types of metals: the monovalent noble metals, and multivalent Al and Mg. Additionally we investigate the stability from a mechanical point of view by measuring the stiffness of atomic contacts. The last chapter is dedicated to electrochemical methods of nanowire fabrication and we explore possible ways of enhancing the nanowire stability.

In this work we investigate the deexcitation process of a slow metastable helium atom (He*) in its triplet state on simple metal surfaces. We compute the electronic properties of the interacting He*-metal (jellium-like) system, using the embedding Green's function method, within the framework of density functional theory. The Auger deexcitation rates are calculated at different distances from the surface using the Fermi golden rule, and the energy distribution of the emitted electrons is obtained by integrating the Auger rates along the classical trajectory followed by the atom in the scattering process. We present the results for three metal surfaces (Al, Na, and Cs) which are sufficiently different to span the distinct deexcitation mechanisms taking place when the He* interacts with the surface: resonant ionization + Auger neutralization for high work function substrates, and Auger deexcitation for low work function ones. Our results for the deexcitation spectral profiles are in good agreement with the experimental ones. (c) 2005 Elsevier B.V. All rights reserved.

In this letter the core-core-valence Auger transitions of an atomic impurity, both in bulk or adsorbed on a jellium-like surface, are computed within a DFT framework. The Auger rates calculated by the Fermi golden rule are compared with those determined by an approximate and simpler expression. This is based on the local density of states (LDOS) with a core hole present, in a region around the impurity nucleus. Different atoms, Na and Mg, solids, Al and Ag, and several impurity locations are considered. We obtain an excellent agreement between KL1V and KL23V rates worked out with the two approaches. The radius of the sphere in which we calculate the LDOS is the relevant parameter of the simpler approach. Its value only depends on the atomic species regardless of the location of the impurity and the type of substrate. (C) 2003 Elsevier B.V. All rights reserved.

Surface energies of aluminium ((1 1 1), (1 1 0) and (1 0 0)) were calculated in second-order perturbation theory based on the jellium model, and by full atomistic models using a Gaussian basis set, in the framework of density functional theory. In both cases, surface energies were extracted from slab calculations using the incremental method, which considers two slabs with consecutive numbers of layers (6 and 7 layers). In the non-perturbative calculation, the fitting method which involves a series of slabs up to 10 layers is also used to examine the limitations of the incremental method and to improve it. Our results are compared with those from other authors and with experiment being the limitations of the perturbative method discussed. The predictions of the stabilized jellium model are also referred to. http://www.sciencedirect.com/science/article/B6TJF-49G5NYD-3/1/ea16c0136c90b33c7ad2c8ab22dfc31f

While keeping the discreteness of the reciprocal space, we calculate the spectrum of incoherent electron-hole excitations in the conducting Fermi liquids. The method is illustrated on the well-known jellium model within the random phase approximation. It also leads to the formulation of a sum rule from which we get the details of the dispersion curve for the collective plasmon mode. The notion of time averaging in the discrete approach is briefly recalled., Računamo spektar nekoherentnih uzbuda elektron-šupljina u vodljivim Fermijevim tekućinama zadržavajući diskretnost recipročnog prostora. Pristup se predstavlja pomoću poznatog modela drhtavice i približenja nasumičnih faza. Dobiva se zbrojno pravilo iz kojeg slijede pojedinosti disperzijske krivulje za kolektivan plazmonski mod. Podsjeća se ukratko na pojam vremenskog prosjeka u ovom diskretnom pristupu.

We present a comparison of the electronic level structure of Cu - n clusters with the jellium model using photoelectron spectroscopy of metal cluster anions. The spectra are recorded at an energy resolution of 30 meV using photon energies of up to 6.4 eV. We obtain a well resolved picture of the electronic structure of the 4s derived electronic states in the energy region between the localized 3d derived states and the highest occupied molecular orbital. The observed features can be assigned to the 1s, 1p, and 1d shells predicted by the jellium model if ellipsoidal distortions and effects like shake-up processes, multiplet splittings and the s–d hybridization are taken into consideration.

We present a selfconsistent calculation of the electron distribution at metal surfaces in the presence of a static electric field in the semi-infinite jellium model. The calculation is based on the Hohenberg-Kohn-Sham theory with a nonlocal approximation for the exchange-correlation energy and potential. For different metallic density rs=2, 3, 4 we present numerical results for the mean position and the spread of the induced charge density. The results for the centroid of the charge induced by a small field are discussed and compared with the image plane position values obtained from the exchange-correlation potential.