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We have simulated large amplitude motion in cyclic one-dimensional lattices of Morse potential oscillators with a mass impurity, and have observed an unexpected persistence of solitary wave behavior for which we are unable to discover a satisfactory explanation. In solitary wave motion as a function of cycle length and of initial energy, the most common feature of the dynamics is an initial energy plateau with regular oscillatory energy exchange between the solitary wave and other excitations of the lattice, followed by rapid decay. Some systems show no decay at all through 1000 impurity interactions, while others show no significant plateau before decaying. For some cycle lengths there are energy bands in which the solitary wave propagates indefinitely long, with small amplitude oscillatory exchange of energy with the lattice. No regularities were found. 相似文献
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This article describes the construction of a natural family of conformally invariant differential operators on a four-dimensional (pseudo-)Riemannian manifold. Included in this family are the usual massless field equations for arbitrary helicity but there are many more besides. The article begins by classifying the invariant operators on flat space. This is a fairly straightforward task in representation theory best solved through the theory of Verma modules. The method generates conformally invariant operators in the curved case by means of Penrose's local twistor transport.S.E.R.C. Advanced Fellow and Flinders University Visiting Research Fellow 相似文献
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Lazarus EA Navratil GA Greenfield CM Strait EJ Austin ME Burrell KH Casper TA Baker DR DeBoo JC Doyle EJ Durst R Ferron JR Forest CB Gohil P Groebner RJ Heidbrink WW Hong R Houlberg WA Howald AW Hsieh C Hyatt AW Jackson GL Kim J Lao LL Lasnier CJ Leonard AW Lohr J La Haye RJ Maingi R Miller RL Murakami M Osborne TH Perkins LJ Petty CC Rettig CL Rhodes TL Rice BW Sabbagh SA Schissel DP Scoville JT Snider RT Staebler GM Stallard BW Stambaugh RD St John HE Stockdale RE Taylor PL Thomas DM 《Physical review letters》1996,77(13):2714-2717
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V.I. Anisimov I.A. Nekrasov D.E. Kondakov T.M. Rice M. Sigrist 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(2):191-201
The electronic structures of the metallic and insulating phases of the alloy series Ca2-xSrxRuO4 ( 0 ?
x
? 2) are calculated using LDA, LDA+U and Dynamical Mean-Field Approximation methods. In the end members the groundstate respectively
is an orbitally non-degenerate antiferromagnetic insulator (x
= 0) and a good metal (x
= 2). For x
> 0.5 the observed Curie-Weiss paramagnetic metallic state which possesses a local moment with the unexpected spin S
= 1/2, is explained by the coexistence of localized and itinerant Ru-4d-orbitals. For 0.2 <
x
< 0.5 we propose a state with partial orbital and spin ordering. An effective model for the localized orbital and spin degrees
of freedom is discussed. The metal-insulator transition at x
= 0.2 is attributed to a switch in the orbital occupation associated with a structural change of the crystal.
Received 27 July 2001 相似文献
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