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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 2 (1981), S. 331-340 
    ISSN: 1572-9567
    Keywords: heat capacity ; high pressure ; silver bromide (AgBr) ; silver chloride (AgCl) ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal conductivity, λ, and the heat capacity per unit volume, ρc p , have been measured for solid silver bromide (AgBr) using the transient hot-wire method. Measurements were made at temperatures in the range 100–400 K and at pressures up to 2 GPa. ρc p was found to be independent of temperature and pressure over these ranges. λ of AgBr was found to be similar to that of AgCl, which was measured previously. For AgBr, only acoustic phonons needed to be taken into account up to 340 K, but optic phonons probably carried some heat at higher temperatures. The Leibfried-Schlömann (LS) formula could describe the ratio λ(AgCl)/λ(AgBr), but not the ratio λ(1 GPa)/λ(0) for either substance. An empirical modification of the LS formula could describe the latter ratios but not the former. Further theoretical developments are required for understanding of λ(P) for even such relatively simple substances as AgCl and AgBr.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 15 (1994), S. 513-524 
    ISSN: 1572-9567
    Keywords: high pressure ; phase behavior ; thermal conductivity urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal conductivity of the solid phases I and III of urea was measured at temperatures in the range 50–370 K for pressures up to 1 GPa. Phase III, previously detected only at pressures above 0.5 GPa, was observed here at low pressures ( 〈0.07 GPa) below about 230 K. Extrapolation of the I–III phase line indicates that phase III might be obtained at 218 K at atmospheric pressure and, consequently, that urea might exhibit two solid phases at atmospheric pressure. The temperature dependence of the thermal conductivity of both phase I and phase III could be described by the Debye model for thermal conductivity assuming phonon scattering by three phonon umklapp processes only. Despite a volume decrease at the I → III transition, the thermal conductivity decreased by about 20%. Normally, thermal conductivity increases at a phase transition at which volume decreases. This rather unusual behavior of urea might be due to an increase in the nearest-neighbor distance at the I → III transition.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 15 (1994), S. 165-176 
    ISSN: 1572-9567
    Keywords: bulk modulus ; crude oil ; glass transition ; heat capacity ; high pressure ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The transitions to the glassy state in viscous crude oils have been investigated at high pressures by the transient hot-wire method, by differential scanning calorimetry, and by equation-of-state measurements. The range of pressures investigated was up to 1.2 GPa in the temperature interval 150–370 K. The glass transition in crude oils is a common phenomenon and occurs due to the viscosity increase on decreasing the temperature or increasing thepressure. The actual transition coordinates depend not only on physical properties but also on the characteristic experimental time.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 6 (1985), S. 101-105 
    ISSN: 1572-9567
    Keywords: adiabatic compression ; calculational procedure ; high pressure ; specific heat capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A procedure is described for calculating specific heat capacity under pressure, c p (T, P), from data for c p (T, 0) and adiabatic (∂T/∂P) s. The main advantage is that (∂T/∂P)s can be readily measured under high-pressure conditions.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 6 (1985), S. 353-365 
    ISSN: 1572-9567
    Keywords: high pressure ; sodium fluoride (NaF) ; thermal conductivity ; transient hot-wire method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal conductivity (λ) of solid NaF has been measured over the temperature (T) range 100–350 K and at pressures (P) up to 2.5 GPa, using the transient hot-wire method. Results for λ(T,P) could be described to a good approximation by the Leibfried-Schlömann formula. It was found that the isochoric temperature derivative of the thermal resistivity W (= λ−1) increased systematically with the mass ratio for the B1-type phases of the sodium and potassium halides.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 2 (1981), S. 289-300 
    ISSN: 1572-9567
    Keywords: heat capacity ; high pressure ; silver chloride (AgCl) ; thermalconductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using the transient hot-wire method, measurements were made for solid AgCl of both the thermal conductivity, λ, and the heat capacity per unit volume, ρc p, where ρ is the mass density. Measurements were made in the temperature range 100 to 400 K, and at pressures up to 2 GPa. c p(P, T) could be adequately described if the acoustic modes were represented by a Debye model and the optic modes by an Einstein model. Analysis of λ(T) showed that only the acoustic modes needed to be taken into account up to 300 K, but that the optic modes were increasingly effective in carrying heat at higher temperatures. λ(P) was adequately described by the Lawson formula, but not by the Leibfried-Schlömann formula, to which it is formally equivalent. Agreement with experiment could be achieved by two different modifications of the Leibfried-Schlömann formula, although neither has a firm theoretical basis.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 829-846 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio averaged relativistic effective core potentials (AREP), spin-orbit (SO) operators, and valence basis sets are reported for the elements Fr through Pu in the form of expansions in Gaussian-type functions. Gaussian basis sets with expansion coefficients for the low-energy states of each atom are given. Atomic orbital energies calculated under the j-j coupling scheme within the self-consistent field approximation and employing the AREP'S in their unaveraged form (REP'S) agree to within 10% of orbital energies due to numerical all-electron Dirac-Fock calculations. The accuracy of the AREP'S and so operators is also shown to be good through comparisons of calculated so splitting energies with all-electron Dirac-Fock results.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 55 (1995), S. 393-410 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio self-consistent-field calculations are reported for electronic states of beryllium clusters comprised of 93, 105, 111, and 123 atoms. The respective clusters correspond to coordination shells 12-15 of a central Be atom with internuclear separations derived from the lattice constants of the bulk metal. Ab initio effective core potentials have been employed to replace the 1 s electrons, thereby reducing the complexity of the calculations. In addition, use of the full D3h point group symmetry of the clusters results in a substantial reduction of the numbers of two-electron integrals that must be computed and processed. Binding energies, orbital energies, electric field gradient, nuclear-electrostatic potential, diamagnetic shielding constant, second moments, and Mulliken populations are calculated for selected electronic states. Calculated binding energies when compared among the different clusters as well as to smaller and larger fragments from earlier studies provide evidence for the onset of convergence to the Hartree-Fock limit of the bulk. Lowest-state ionization potentials are consistently above and agree to within 14% of the experimental workfunction. The net charge on the central beryllium atom decreases toward zero. The variability of observed bulklike behavior for the different properties indicates that the transition between cluster and bulklike behavior is not sharp and depends on the quantity of interest. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 41 (1992), S. 733-747 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hartree-Fock-Roothaan studies are reported for low-lying electronic states of metallic beryllium as modeled by a moiety of 135 beryllium atoms. The system corresponds to 16 coordination shells of a central Be with internuclear separations derived from the lattice constants of the bulk metal. The calculations become tractable by use of the full D3h symmetry of the system at both the integrals and self-consistent-field stages and by employing ab initio effective potentials for the 1s electrons of each beryllium atom. Ionization potentials, binding energies, orbital energies, electric field gradients, nuclear-electrostatic potentials, diamagnetic shielding constants, second moments, and Mulliken populations are calculated for selected electronic states. The calculated ionization potential for the lowest state agrees to within 10% of the experimental bulk work function. A density-of-states analysis for that state is reported and compared with band structure calculations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 38 (1990), S. 225-240 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio self-consistent field calculations are reported for electronic states of beryllium clusters comprised of 81 and 87 atoms. The clusters correspond to the tenth and eleventh coordination shells of a central Be with internuclear separations derived from the lattice constants of the bulk metal. Ab initio effective core potentials have been employed to replace the 1s electrons, therey reducing the complexity of the calculations. In addition, the use of the full D3h point group symmetry of the clusters results in a substantial reduction of the number of two-electron integrals that must be computed and processed. Binding energies, orbital energies, electric field gradient, nuclear-electrostatic potential, diamagnetic shielding constant, second moments, and Mulliken populations are calculated for selected electronic states. Systematic trends toward bulk behavior with increasing cluster size, as found in earlier cluster studies, continue to appear for the electric field gradient and quadrupole moment of Be81. Anomalous behavior, however, is observed in Be87. This is attributed to distortional effects due to the addition of atoms in planes above and below the Be81 cluster along the principal axis of symmetry.
    Additional Material: 4 Ill.
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