We present a short review of the current status of electronic structure calculations for ordered solid surfaces. For the $s-p$ bonded metal surfaces, emphasis is centered entirely on self-consistent field (SCF) calculations employing a local density approximation for exchange and correlation. For semiconductor surfaces both SCF and empirical tight-binding methods are discussed, while for transition metal surfaces, where no SCF calculations have been carried out, a number of different schemes for solving Schrödinger's equation at a surface are reviewed that use plausible but not self-consistent forms for the surface potential. Finally, calculations for chemisorbed systems are briefly covered, with emphasis on ordered monolayers on semiconductor and transition metal surfaces.

Heavy ion experiments are already enriching nuclear science with a tapestry of new phenomena which require explanation. In response, theoretical nuclear physics is rapidly expanding its insights to encompass these new observations, especially those concerned with the macroscopic aspects. Preliminary theoretical studies already suggest that the dynamical nuclear fluid must sometimes be considered viscous, compressible, and/or rotational, if its microscopic properties are to be encompassed. These and some threads already well placed in the picture will be discussed. Other reasons will be cited to support the expectation that theoretical nulear macroscopists may more and more come to be fluid dynamicists who specialize in those few thousand fluids called nuclei. Three such reasons are (a) the promised richness of their structure as dynamical fluids, (b) their unique prospect, among all the objects of modern physical science, of allowing a complete microscopic, as well as a phenomenological macroscopic, description, and (c) the possible overflow of such nuclear implications into classical fluid theory, from the viewpoint of which the nuclear heavy ion data are a significant novelty.

This is a review of the salient features of high energy diffraction scattering of hadrons. It begins with a summary of the experimental situation for those processes which persist at very high energies—the diffractive processess—and defines the underlying exchange mechanism called the Pomeron. A review is made of the key features of the multiperipheral model, since it lies at the beginning of all studies of diffraction. Its virtues and blemishes are exposed. Then we turn to various models which attempt to add unitarity to the multiperipheral model. From the point of view of the direct channel we consider absorptive models, eikonal models, and the multiperipheral bootstrap. The $t$ channel is taken next, and an exposition of the formulation and major results of Reggeon field theory is given. "Et fut une digne parole de Julius Brusus aux ouvriers qui lui offraient pour trois mille écus mettre sa maison en tel point que ses voisins n'y auraient plus la vue qu'ils y avaient: `Je vous en donnerai,' dit-il, `six mille, et faites que chacun y voie de toutes parts.' " de Montaigne, M. (1585-88), "Du repentir"

A mainly didactic discussion is given of the mechanism for the gradual build up of transverse polarization of electrons and positrons in storage rings. The history and basic results are reviewed briefly. Then an intuitive explanation of the polarization in terms of spontaneous emission via a nonrelativistic magnetic dipole transition in a moving inertial frame is presented and criticized. This simple treatment contains a large part of the essential physics, but not all. It is surprisingly successful for electrons and positrons ($g=2\mathrm{}$), becomes exact for large $g$ factors of either sign, but fails badly for particles with $g$ factors of the range $0\lesssim g\lesssim 1.5$. The failure occurs because here the spin-magnetic-moment system cannot be treated even approximately in isolation from the orbital motion. A correct semiclassical description of radiation by a spin system is then given, in direct analogy with semiclassical radiation theory for charged particles ignoring spin. The classical equation of motion for a spin in relativistic motion, derived originally by Thomas, is used to obtain an effective Hamiltonian of interaction of a spin with electromagnetic fields. Emission and absorption of radiation is then described by replacing the classical electromagnetic fields with the appropriately normalized photon fields. The resulting formulas are applicable to charged particles of arbitrary $g$ factor. Expressions are given for the differential spectra in angle and in frequency for numbers of photons and for radiated power, as well as the previously known results for the total transition rates. These results seem of physical interest only for $g=2\mathrm{}$ but serve useful pedagogic purposes, refuting some of the expectations of the naive explanation. The various differential spectra are treated in detail for $g=2\mathrm{}$ and compared with the corresponding spectra for ordinary synchrotron radiation.

A generalization of Einstein's gravitational theory is discussed in which the spin of matter as well as its mass plays a dynamical role. The spin of matter couples to a non-Riemannian structure in space-time, Cartan's torsion tensor. The theory which emerges from taking this coupling into account, the $U_4$ theory of gravitation, predicts, in addition to the usual infinite-range gravitational interaction medicated by the metric field, a new, very weak, spin contact interaction of gravitational origin. We summarize here all the available theoretical evidence that argues for admitting spin and torsion into a relativistic gravitational theory. Not least among this evidence is the demonstration that the $U_4$ theory arises as a local gauge theory for the Poincaré group in space-time. The deviations of the $U_4$ theory from standard general relativity are estimated, and the prospects for further theoretical development are assessed.

This review of the properties of leptons, mesons, and baryons is an updating of Review of Particle Properties, Particle Data Group [Phys. Letters 50B, No. 1 (1974), and Supplement, Rev. Mod. Phys. 47 (1975) 535]. Data are evaluated, listed, averaged, and summarized in tables. Numerous tables, figures, and formulae of interest to particle physicists are also included. A data booklet is available.

This is a review and study of the absorption model approach to two-body hadron reactions. The basic view is that reactions proceed by Reggeized particle exchange, modified by (mainly) absorptive initial and final state interactions. Our approach is pedagogical in two respects. First, the conceptual basis of the approach is discussed in detail, and considerable emphasis is put on spin properties and relating amplitudes and observables. We attempt to explain the procedures in sufficient detail that the interested reader can apply them. Limitations and theoretical weaknesses of the approach are discussed. Second, by approaching the whole field of two-body hadron reactions from one viewpoint, we can give unified treatments of some areas, such as polarizations, and of many observables and regularities, and unified explanations of why the data behave as they do from the viewpoint of the model. Because our purpose is primarily pedagogical, we consider representative reactions and amplitudes rather than exhaustively discuss data. At least one example of every major kind of amplitude is discussed, so the extension to additional reactions is often qualitatively possible without further calculation.

The dissipation induced by coulomb-collisional scattering provides an irreducible minimum, and thus a useful standard for comparison, for transport processes in a hot, magnetically confined plasma. The kinetic description of this dissipation is provided by an equation of the Fokker-Planck form. As in the standard transport theory for a neutral gas, approximate solution of the Fokker-Planck equation permits the calculation of transport coefficients, which linearly relate the fluxes of particles, energy, and electric charge, to the density and temperature gradients, and to the electric field. The transport relations are useful in studying the confinement properties of present and future experimental devices for research in controlled thermonuclear fusion. The transport theory for a magnetized plasma (in which the Larmor radius is much smaller than gradient scale lengths describing the plasma fluid) departs from the theory for a neutral gas in several fundamental ways. Thus, transport coefficients for a magnetized plasma can be calculated even when the collisional mean free path is much longer than the gradient scale length (as would pertain in thermonuclear regimes). Such transport coefficients are generally nonlocal, being defined in terms of averages over surfaces with macroscopic dimensions. Furthermore, when the mean free path is long, the magnetized-plasma transport coefficients depend crucially upon the magnetic field geometry, the effects of which must be treated at the kinetic level of the Fokker-Planck equation. The results display several novel couplings between collisional dissipation and the electromagnetic field. The present review of magnetized-plasma transport theory is intended to be as widely accessible as possible. Thus the relevant features of magnetic confinement in closed (toroidal) systems, and of charged particles in spatially varying fields, are derived, at least in outline, from first principles. Although consideration is given to "classical" transport in which most field geometric effects are omitted, major emphasis is placed on the "neoclassical" theory which has been developed over the last decade. Neoclassical transport coefficients are specifically relevant to a magnetically confined plasma, rather than to just a magnetized plasma; their unusual features, such as nonlocality and geometry dependence, become particularly important in the high temperature regime of proposed thermonuclear reactors. The area of neoclassical theory which seems most complete—its application to axisymmetric tokamak-type confinement systems—is correspondingly stressed.

In a number of rare-earth compounds, the atomic-like $f$ levels and the wide $s-d$ band coexist at the Fermi level. Such compounds are being referred to as mixed-valence compounds. These compounds have a variety of unique thermal and magnetic properties. In this article, we review some salient experimental results in such compounds and discuss a theoretical framework in which they may be understood. Special emphasis is given to the Samarium chalcogenides, on which extensive experimental results are available. The review is not meant to be a comprehensive survey of theoretical and experimental results. Rather it reflects the interests of the author. The hope is that the basic unresolved issues in the theory of mixed-valence compounds are pointed out so as to stimulate further experimental and theoretical work.

Two-body matrix elements of the residual nucleon-nucleon interaction are extracted from experimental data throughout the periodic table and are used to determine the ranges and well depths of various components of a local interaction. The $T=1\mathrm{}$ even and odd components of the central interaction both definitely require two wells with different ranges; a shorter-range attractive well with a longer-range repulsive one. The need for a tensor interaction and a two-body spin-orbit interaction is also explored and their inclusion improves the fit slightly.

This paper reviews the present state of the problem of the origin of cosmic rays. Primary attention is paid to galactic diffusion models with a halo, and questions of cosmic-ray chemical composition, electron component, and synchrotron galactic radioemission. The authors' conclusion is that models with a large halo with a characteristic cosmic-ray age $T_{\mathrm{cr}}\sim {10}^8$ years are confirmed by radio data, and at least do not contradict the information on cosmic-ray chemical composition. The paper also deals with the problems of anisotropy, plasma phenomena in cosmic rays, and the prospects of gamma-ray astronomy.

The fundamental role of Eckart vectors and Eckart frames is demonstrated in the theory of the vibration-rotation Hamiltonian for a polyatomic molecule.

We present a unified discussion and illustrations of the electron-optical aspects of electron penetration into, or escape from, the inner region of atoms. Both processes may focus or defocus the amplitudes of wavefunctions and shift their phases, as manifested in countless phenomena ranging from level shifts to $\beta$-decay rates. A background survey begins by discussing the Fermi-Segrè formula for hyperfine splittings and emphasizes the interplay of hydrogenic and WKB approximations. The Phase-Amplitude Method, which determines amplitude ratios and phase shifts directly, proves useful for interpreting the systematics of these parameters along the Periodic System. We present results of survey calculations, carried through the Periodic System using Hartree-Slater potential fields, of: (a) $\frac{{\alpha }_l\mathrm{}\left(0\right)\mathrm{}}{{\alpha }_l\left(\infty \right)}$, the ratio of the wavefunction's amplitude at $r=0\mathrm{}$ to that outside the atom; (b) ${\delta }_l\mathrm{}(E=0\mathrm{})\mathrm{}$ and ${\frac{d{\delta }_l}{\mathrm{dE}}|}_{E=0\mathrm{}}$, the phase shift and its energy derivative at $E=0\mathrm{}$, and (c) the changes in ${\delta }_l\mathrm{}(E=0\mathrm{})\mathrm{}$ and $\frac{{\alpha }_l\mathrm{}\left(0\right)\mathrm{}}{{\alpha }_l\left(\infty \right)}$ induced by either a unit perturbation localized near $r=0\mathrm{}$ or a relativistic correction. Thus we provide a broad mapping of certain fundamental parameters based on rather crude but realistic calculations. These results are meant to serve as a bench mark in surveying problems and in checking new results, while standard methods are preferable for working out specific applications accurately.

A survey is given of the available cross-section data for ionization of inner-shell electrons by incident electrons in the range of interest for electron-probe microanalysis and for Auger-electron spectroscopy of solid surfaces. Owing to the paucity of data, the bulk of the discussion is limited to $K$-shell and $L$-shell ionization of light atoms. Calculated, semiempirical, and experimental cross-section data have been intercompared graphically and through fits to the linearized Bethe equation for inner-shell ionization (the Fano plot). Almost all of the data could be satisfactorily fitted over the range $4\lesssim U_{\mathrm{nl}}\lesssim 30$, where $U_{\mathrm{nl}}=\frac{E_0}{E_{\mathrm{nl}}}$, $E_0$ is the incident electron energy, and $E_{\mathrm{nl}}$ the binding energy of electrons in the $\mathrm{nl}$ shell. From these fits, values could be obtained of the "effective" Bethe parameters $b_{\mathrm{nl}}$ and $c_{\mathrm{nl}}$. Values of the parameter $b_{\mathrm{nl}}$ have also been derived from photoabsorption data and were found to be generally consistent with the ionization data if account was taken of the distribution of differential oscillator strength with respect to excitation energy and the consequent expected variation of $b_{\mathrm{nl}}$ with incident electron energy. The derived "effective" Bethe parameters should not therefore be used outside the range of each fit.