Self-consistent and quasiharmonic approximations: The equation of state and the high temperature lattice instability

The self-consistent average-phonon (SCAP) treatment, developed in earlier papers for monoatomic solids was extended to the alkali halides for which self-consistent calculations were not available. The quantitative comparison of SCAP with an average quaiharmonic (AQH) treatment for Ar and for NaCl showed that AQH highly overestimated the thermal pressure. Because of this overestimation, we conclude that the lattice instability reported by Boyer for NaCl, which he considered to be related to melting, is a consequence of using a quasiharmonic approximation.     

Observation of sustained self-pulsation in CW operated flaredY-coupled laser arrays

The time evolution of the near-field radiation patterns of CW operated inphase locked flared `Y' coupled diode laser arrays has been observed with a streak camera. The arrays exhibit sustained self-pulsation at frequencies as high as 4 GHz     

Advances in diode laser pumps

Diode laser pumps for solid-state lasers are reviewed with special emphasis on current and future capabilities. Included are discussions of pumps for CW (continuous-wave) and quasi-CW operation, and end- and side-pumping configurations     

Dilepton and strange particles production by neutrinos in gargamelle

New results are presented of an analysis of pictures taken during an exposure of Gargamelle to the CERN ν beam in 1975. In addition to three ν_μ+N→μ^?+e⁺+V⁰+ hadrons events previously reported, an excess is found of events of the type ν_μ+N→μ^?+e⁺+ hadrons without V⁰. An analysis of strange particle production in charged current events suggests a possible violation of the ΔS=ΔQ rule. Interpreted in terms of charm production, the data permit an estimate of branching ratios and production rate of charmed particles. A limit is also placed on charmed particle production by neutral currents.     

A molecular dynamical study of the equation of state of solids at high temperature and pressure

The molecular dynamics method of computer simulation was used to study the pressure and energy as a function of volume and temperature for f.c.c. neon with 6–12 Lennard-Jones interatomic forces and for b.c.c. iron with Morse interatomic forces. A self-consistent cell model was used to derive analytical formulae which describe the results of the computer experiments. A method for correcting the inherently classical results of the molecular dynamics calculations for the effect of quantum statistics is proposed. The results of the calculations are compared with experimental data and with various approximate methods for calculating the Grüneisen constant.     

The self-consistent cell model equation of state for solids

An anharmonic equation of state for solids using the Self-Consistent Cell Model (SCCM) is given in a form useful for calculating the usual thermodynamic properties. Following Cowley and Shukla, using the Jaswal-Girifalco potential for copper, calculations are compared with other models and with experiment. The results from the analytic expressions using the SCCM are as good or better than those obtained from far more complicated theories of anharmonicity. Using the Lindemann criterion, the pressure at the melting point was obtained as a function of the melting temperature. A melting line was also obtained for iron and the longitudinal velocity and isothermal bulk modulus along the melting line were calculated. The Hugoniot pressures were calculated and compared with experiment. For both the copper and iron the agreement between theory and experiment is remarkably good considering the empirical nature of the potentials, the simplifying approximations of the SCCM calculations, and the large range of densities and pressures that are compared with experiment.     

Die Adsorption organischer Verbindungen an Raney-Nickel

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