Modules élastiques des métaux de transition
About: This article is published in Journal De Physique.The article was published on 1970-11-01. It has received 344 citations till now.
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465 citations
TL;DR: A review of the current theoretical understanding of collective and single particle diffusion on surfaces and how it relates to the existing experimental data can be found in this article, where a brief survey of the experimental techniques that have been employed for the measurement of the surface diffusion coefficients is presented.
Abstract: We review in this article the current theoretical understanding of collective and single particle diffusion on surfaces and how it relates to the existing experimental data. We begin with a brief survey of the experimental techniques that have been employed for the measurement of the surface diffusion coefficients. This is followed by a section on the basic concepts involved in this field. In particular, we wish to clarify the relation between jump or exchange motion on microscopic length scales, and the diffusion coefficients which can be defined properly only in the long length and time scales. The central role in this is played by the memory effects. We also discuss the concept of diffusion under nonequilibrium conditions. In the third section, a variety of different theoretical approaches that have been employed in studying surface diffusion such as first principles calculations, transition state theory, the Langevin equation, Monte Carlo and molecular dynamics simulations, and path integral formalism...
445 citations
01 Jan 2002
TL;DR: A review of the current theoretical understanding of collective and single particle diA usion on surfaces and how it relates to the existing experimental data can be found in this article, where a brief survey of the experimental techniques that have been employed for the measurement of the surface correlation coefficients is presented.
Abstract: We review in this article the current theoretical understanding ofcollective and single particle diA usion on surfaces and how it relates to the existing experimental data. We begin with a brief survey of the experimental techniques that have been employed for the measurement of the surface diA usion coeA cients. This is followed by a section on the basic concepts involved in this ®eld. In particular, we wish to clarify the relation between jump or exchange motion on microscopic length scales, and the diA usion coeA cients which can be de®ned properly only in the long length and time scales. The central role in this is played by the memory eA ects. We also discuss the concept of diA usion under nonequilibrium conditions. In the third section, a variety of diA erent theoretical approaches that have been employed in studying surface diA usion such as ®rst principles calculations, transition state theory, the Langevin equation, Monte Carlo and molecular dynamics simulations, and path integral formalism are presented. These ®rst three sections form an introduction to the ®eld of surface diA usion. Section 4 contains subsections that discuss surface diA usion for various systems which have been investigated both experimentally and theoretically. The focus here is not so much on speci®c systems but rather on important issues concerning diA usion meas
400 citations
TL;DR: A review of stability criteria, thermodynamic functions in the vicinity of an instability, and how instabilities may arise or disappear when pressure, temperature, and/or chemical composition is varied are discussed in this article.
Abstract: Most metallic elements have a crystal structure that is either body-centered cubic (bcc), face-centered close packed, or hexagonal close packed. If the bcc lattice is the thermodynamically most stable structure, the close-packed structures usually are dynamically unstable, i.e., have elastic constants violating the Born stability conditions or, more generally, have phonons with imaginary frequencies. Conversely, the bcc lattice tends to be dynamically unstable if the equilibrium structure is close packed. This striking regularity essentially went unnoticed until ab initio total-energy calculations in the 1990s became accurate enough to model dynamical properties of solids in hypothetical lattice structures. After a review of stability criteria, thermodynamic functions in the vicinity of an instability, Bain paths, and how instabilities may arise or disappear when pressure, temperature, and/or chemical composition is varied are discussed. The role of dynamical instabilities in the ideal strength of solids and in metallurgical phase diagrams is then considered, and comments are made on amorphization, melting, and low-dimensional systems. The review concludes with extensive references to theoretical work on the stability properties of metallic elements.
398 citations
TL;DR: The semi-empirical tight binding model as mentioned in this paper is the simplest scheme for describing the energetics of semi-conductors and transition metals within a quantum mechanical framework, and it has been used for many applications.
Abstract: The semi-empirical Tight Binding model1,2 is the simplest scheme for describing the energetics of semi-conductors and transition metals within a quantum mechanical framework.
346 citations
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TL;DR: In this paper, the LCAO interpolation method was used as an interpolation technique in connection with more accurate calculations made by the cellular or orthogonalized plane-wave methods.
Abstract: The LCAO, or Bloch, or tight binding, approximation for solids is discussed as an interpolation method, to be used in connection with more accurate calculations made by the cellular or orthogonalized plane-wave methods. It is proposed that the various integrals be obtained as disposable constants, so that the tight binding method will agree with accurate calculations at symmetry points in the Brillouin zone for which these calculations have been made, and that the LCAO method then be used for making calculations throughout the Brillouin zone. A general discussion of the method is given, including tables of matrix components of energy for simple cubic, face-centered and body-centered cubic, and diamond structures. Applications are given to the results of Fletcher and Wohlfarth on Ni, and Howarth on Cu, as illustrations of the fcc case. In discussing the bcc case, the splitting of the energy bands in chromium by an antiferromagnetic alternating potential is worked out, as well as a distribution of energy states for the case of no antiferromagnetism. For diamond, comparisons are made with the calculations of Herman, using the orthogonalized plane-wave method. The case of such crystals as InSb is discussed, and it is shown that their properties fit in with the energy band picture.
3,696 citations
TL;DR: In this paper, the authors present a compilation of physical properties used in alloying theory, including magnetic susceptibility, electrical resistivity, and thermal conductivity, as well as some interrelationships of the physical properties.
Abstract: Publisher Summary The physical properties given in this compilation are listed in the accompanying tabulation according to the table given in this chapter in which they can be found. Values for two quantities that have frequently been used in alloying theory studies, viz., the metallic radius and electronegativity, are not included here. Other properties, such as magnetic susceptibility, electrical resistivity, and thermal conductivity, which are generally of interest to those studying solids, are not included in this compilation primarily because such properties do not appear to be important in alloying theory. The derived properties and some interrelationships of the physical properties are examined and discussed in this chapter. Those subjects which also appear in tabulated form are listed in the accompanying tabulation. The initial goal in our alloy-theory program was a set of Gruneisen constants and a set of size factors. To calculate these quantities, almost all of the physical properties given herein are needed in the computations. Some of the other derived quantities are not only intermediate steps in the computations of the Gruneisen constant and size factor, but also serve as checks on the consistency of initial data (i.e., the measured physical properties of the elements). Some of the “constants” of the elements—that is, the Griineisen constant, entropy of fusion, etc., which have been derived for a few elements and then generally assumed to apply to all elements—are examined to see if this generalization is valid.
760 citations
658 citations
TL;DR: S-D interaction in electronic band structure of transition metals represented by model Hamiltonian, treating copper band structure as discussed by the authors, is considered in this paper. But it is based on model Hamiltonians.
Abstract: S-D interaction in electronic band structure of transition metals represented by model Hamiltonian, treating copper band structure
480 citations
TL;DR: The elastic constants of anisotropic materials have been studied in this article, where the elastic constants are defined as the ratio of the elasticity of a given material to its elasticity.
Abstract: (1956). The elastic constants of anisotropic materials—II. Advances in Physics: Vol. 5, No. 19, pp. 323-382.
265 citations