101,922 research outputs found
Pair correlations and exchange phenomena in the free electron gas
No full textFriesecke, G.. (1996). Pair correlations and exchange phenomena in the free electron gas. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/2980
On the problem of two linearized wells
No full textWe study the behaviour of sequences of elastic deformations y : Ω ⊂ ℝn → ℝn whose gradients approach two linearized wells, and give an application to magnetostriction
Crystallization in Two Dimensions and a Discrete Gauss–Bonnet Theorem
No full textWe show that the emerging field of discrete differential geometry can be usefully brought to bear on crystallization problems. In particular, we give a simplified proof of the Heitmann–Radin crystallization theorem (Heitmann and Radin in J Stat Phys 22(3):281–287, 1980), which concerns a system of N identical atoms in two dimensions interacting via the idealized pair potential V(r) = + ∞ if r 1. This is done by endowing the bond graph of a general particle configuration with a suitable notion of discrete curvature, and appealing to a discrete Gauss–Bonnet theorem (Knill in Elem Math 67:1–7, 2012) which, as its continuous cousins, relates the sum/integral of the curvature to topological invariants. This leads to an exact geometric decomposition of the Heitmann–Radin energy into (i) a combinatorial bulk term, (ii) a combinatorial perimeter, (iii) a multiple of the Euler characteristic, and (iv) a natural topological energy contribution due to defects. An analogous exact geometric decomposition is also established for soft potentials such as the Lennard–Jones potential V(r) = r- 6- 2 r- 12, where two additional contributions arise, (v) elastic energy and (vi) energy due to non-bonded interactions
Passage from quantum to classical molecular dynamics in the presence of Coulomb interactions
No full textWe present a rigorous derivation of classical molecular dynamics (MD) from quantum
molecular dynamics (QMD) that applies to the standard Hamiltonians of molecular
physics with Coulomb interactions. The derivation is valid away from possible electronic
eigenvalue crossings
Explicit large nuclear charge limit of electronic ground states for Li, Be, B, C, N, O, F, Ne and basic aspects of the periodic table
No full textThis paper is concerned with the Schrödinger equation for atoms and ions with to 10 electrons. In the asymptotic limit of large nuclear charge , we determine explicitly the low-lying energy levels and eigenstates. The asymptotic energies and wavefunctions are in good quantitative agreement with experimental data for positive ions, and in excellent qualitative agreement even for neutral atoms (). In particular, the predicted ground state spin and angular momentum quantum numbers ( for He, Be, Ne, for H and Li, for N, for B and F, and for C and O) agree with experiment in every case. The asymptotic Schrödinger ground states agree, up to small corrections, with the semiempirical hydrogen orbital configurations developed by Bohr, Hund, and Slater to explain the periodic table. In rare cases where our results deviate from this picture, such as the ordering of the lowest and states of the carbon isoelectronic sequence, experiment confirms our predictions and not Hund's
Derivation of nonlinear bending theory for shells from three-dimensional nonlinear elasticity by Gamma-convergence
No full textWe show that the nonlinear bending theory of shells arises as a Gamma-limit of three-dimensional nonlinear elasticity
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
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