We have simulated the cooling of Lennard-Jones fluids from liquid temperatures to below the glass transition by using molecular-dynamics calculations and periodic boundary conditions. At higher temperatures the "inherent" structure is independent of temperature, but slightly above the glass transition temperature $T_g$ the structure changes and local fivefold symmetry becomes more prominent. At $T_g$ this process is slow and a hysteresis is observed on heating. The low-temperature two-component glass has a cluster of interpenetrating and face-sharing icosahedra percolating throughout the sample.

Studies of the IR vibrational spectroscopy of single crystals of the H-bonded quinhydrone chargetransfer complexes show that a new phase transition occurs upon application of hydrostatic pressure, associated with the proton transfer in the 2D proton lattice. The temperature- and pressure-induced changes in the O-H vibrational spectra are accounted for in terms of the melting of the proton lattice due to the proton tunneling effect.

There is no fundamental reason that fluids should not be ferroelectric. However, the only knownferroelectric fluids are chiral smectic-$C$ liquid crystals and related structures. We examine the possibility that molecules with permanent dipole moments can form a ferroelectric nematic phase, the least ordered conceivable ferroelectric phase. We show that reasonable electric dipole interactions between diskshaped molecules may lead to such a phase, and calculate the phase diagram using mean-field theory. Some constraints on the constituent molecules are discussed.

The diffusion rate of H and D in Nb is calculated with avoidance of the usual adiabatic, linear-coupling, and Condon approximations. The method employed is a generalization of the standard small-polaron theory with explicit account taken of the coupled interstitial-host vibrations. It is applicable in the medium temperature regime, $50 \mathrm{K}\le T\le 300 \mathrm{K}$, and is not limited to light interstitials. Whereas a harmonic calculation exhibits the qualitative features, anharmonic terms have to be included to get quantitative results.

We present results of the first numerical study of the Cahn-Hilliard equation in three dimensions. We study the asymptotic time dependence of the characteristic domain size $R\left(t\right)\mathrm{}$, as well as the scaling of the pair correlation function and the structure factor. The results indicate that dynamical scaling holds at sufficiently late times and that the data for $R\left(t\right)\mathrm{}$ are consistent with a Lifshitz-Slyozov growth law $R\left(t\right)\mathrm{}\sim t^{\frac{1}{3}}$.

A new method to measure the magnetization dependence of the viscosity in polarized liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is presented. The magnetization is obtained by "brute-force polarization" at 45 mK in magnetic fields up to 11 T; it is subsequently destroyed by saturation of the NMR signal. Our result, a relative increase of the viscosity of (3±1.5)×${10}^{-3\mathrm{}}$ at 3.9% polarization and a pressure of 30 bars, disagrees with a prediction based on the "nearly metamagnetic" model.

Excitation spectra of visible luminescence in CsF (2.5-5.6 eV), CsCl (3.9-6.0 eV), CsBr (4.4-6.2 eV), and RbF (2.6-6.2 eV) have been measured at room temperature with use of synchrotron radiation for the energy range up to 40 eV. It is shown that the excitation thresholds of these luminescence bands are located at the transition energies from the outermost-core band to the conduction band. This fact provides direct evidence for the radiative decay of valence electrons into outermost core holes in which the Auger decay process is energetically impossible in these materials.

We investigate a single electron drifting in a thermal crystal under an applied electric field with the applied field and the electron-phonon interaction being treated nonperturbatively. With the help of the path-integral approach of the nonequilibrium Green's function, we derive a set of coupled equations to describe consistently the drift motion and fluctuation where the balance of momentum is consistent with the balance of energy. By solving these equations we obtain various aspects of the nonlinear nonequilibrium electron transport properties.

Angle- and temperature-dependent surface extended x-ray-absorption fine-structure measurements for the $\frac{p4g(2\mathrm{}\times 2)\mathrm{N}}{\mathrm{Ni}\mathrm{}\left(100\right)\mathrm{}}$ structure reveal a strong local vibrational anisotropy of the fivefold-bonded N atoms. At room temperature we find clear evidence for anharmonic vibrations of N relative to its four in-plane Ni neighbors while the vibrations along the fifth bond remain harmonic. This is directly linked to the strong surface reconstruction induced by the chemisorption process. The out-of-plane vibration of the N atom is discussed in terms of an Einstein model.

An explanation is provided for the Mössbauer measurements on Yb${\mathrm{Cu}}_2$${\mathrm{Si}}_2$ by which the temperature-dependent quadrupole moment $Q\left(T\right)\mathrm{}$ of Yb is obtained. The quadruple splitting of the ${}_{}{}^{174}{}_{}{}^{}\mathrm{Yb}$ Mössbauer line is a direct probe of the noncubic crystalline electric field. We compute $Q\left(T\right)\mathrm{}$ by using the noncrossing approximation to a Green's-function formulation of the Anderson impurity problem. The observed $Q\left(T\right)\mathrm{}$ behavior is well reproduced by our theory. The zero-temperature value $Q\left(0\right)\mathrm{}$ is discussed within the frame of the variational ground state proposed by Varma and Yafet and by Gunnarsson and Schönhammer.

We discuss the formation of nontopological solitons in a second-order phase transition in the early Universe. Ratios of dimensionless coupling constants in the Lagrangean determine their abundance and mass. For a large range of parameters, nontopological solitons can be cosmologically significant, contributing a significant fraction of the present mass density of the Universe.

We prove that perturbation theory for the bosonic string diverges for arbitrary values of the coupling constant and is not Borel summable. This divergence is independent of the existence of the infinities that occur in the theory due to the presence of tachyons and dilaton tadpoles. We discuss the physical implications of such a divergence.

A chiral gauge-invariant lattice fermion action is derived from a chiral gauge-variant Wilson fermion action without change in its partition function. By use of this action it is shown that anomalous gauge theories in four dimensions are renormalizable. An application to the chiral Schwinger model shows that it is unitary for a range of Wilson parameter $r$.

We show that chiral gauge theories can be put on a lattice by exploiting the idea of adding extra degrees of freedom. We also examine the lattice chiral Schwinger model to find that the gauge interaction imposes a restriction on the values of a parameter peculiar to the lattice fermion.

We have observed the production of the $D_s^{}{}_{}{}^{\pm }$ by a high-energy neutron beam on nuclear targets. The $D_s^{}{}_{}{}^{\pm }$ was observed in the decay mode $D_s^{}{}_{}{}^{\pm }\to \phi {\pi }^{\pm }$, $\phi \to K^{+}{K}^{-}$. The average of the inclusive cross sections for $D_s^{}{}_{}{}^{+}$ and $D_s^{}{}_{}{}^{-}$ hadroproduction is measured to be $\frac{\mathrm{Bd}\sigma }{d{x}_{\mathrm{F}}}=2.85\mathrm{}\pm 0.80\pm 0.86$ μb/nucleon at $x_{\mathrm{F}}=0.175\mathrm{}$ on the assumption of a linear $A$ dependence, where $B\equiv \frac{\Gamma (D_s^{}{}_{}{}^{\pm }\to \phi {\pi }^{\pm })}{\Gamma (D_s^{}{}_{}{}^{\pm }\to \mathrm{all})}$.

The production of the $\frac{J}{\psi }$ resonance in 125-GeV/c $\overline{p}$ and ${\phi }^{-}$ interactions with Be, Cu, and W targets has been measured. The cross section per nucleon for $\frac{J}{\psi }$ production is suppressed in W interactions relative to the lighter targets, especially at large values of Feynman $x$, which is opposite to the expectation from the various explanations of the European Muon Collaboration effect. Models incorporating modifications of the gluon structure functions in heavy targets show qualitative agreement with the data.

The apparent characteristic temperature observed in the fragmentation of highly excited nuclei is studied by calculations using a simple model consisting of an expanding and emitting source. A characteristic temperature for emission, nearly independent of the initial temperature, is found in the calculations, and the underlying physics is interpreted. This temperature is consistent with the values found in experiments which seem independent of bombarding energy.

At moderate temperatures in nuclei (≅0.5 MeV), there is evidence for damping effects in the rotational behavior. Instead of normal rotational bands, each state can emit any one of a distribution of $\gamma$-ray energies whose FWHM is called the damping width. At higher temperatures, there are expected to be motional narrowing effects, where the damping widths decrease with further increases in temperature. We do not find such a narrowing in the experimental damping widths.

This paper reports the first demonstration of nuclear orientation of radon atoms. The method employed was spin exchange with potassium atoms polarized by optical pumping. The radon isotopes were produced at the ISOLDE isotope separator of CERN. The nuclear alignment of ${}_{}{}^{209}{}_{}{}^{}\mathrm{Rn}$ and ${}_{}{}^{223}{}_{}{}^{}\mathrm{Rn}$ has been measured by observation of $\gamma$-ray anisotropies and the magnetic dipole moment for ${}_{}{}^{209}{}_{}{}^{}\mathrm{Rn}$ has been measured by the nuclear-magnetic-resonance method to be $\left|\mu \mathrm{}\right|=0.83881\left(39\mathrm{}\right)\mathrm{}{\mu }_N$.

We have demonstrated the specular reflection of Na atoms at a nonuniform laser field, the reflection coefficient of the "atomic mirror" being close to 100%. A specific feature of the reflection process is its quantum-state-selective character. The experimentally measured reflection selectivity (the ratio between the reflection coefficients of the sodium atoms in the ground-state sublevels with $F=2\mathrm{}$ and $F=1\mathrm{}$ was around 100.