Eckard Bich - Academia.edu (original) (raw)

Papers by Eckard Bich

Zeitschrift für Physikalische Chemie, 1984

Der zweite Virialkoeffizient von Ethanoldampf wurde bestimmt durch Druckmessungen in Abhängigkeit... more Der zweite Virialkoeffizient von Ethanoldampf wurde bestimmt durch Druckmessungen in Abhängigkeit von der Temperatur bei bekanntem konstantem Volumen und gekannter konstanter Masse der Proben. Die erhaltenen Werte sind für den Temperaturbereich 348 ... 573 K tabelliert.

Journal of Molecular Liquids, Nov 1, 2007

The heat capacity of levoglucosan was measured over the temperature range (5 to 370) K by adiabat... more The heat capacity of levoglucosan was measured over the temperature range (5 to 370) K by adiabatic calorimetry. The temperatures and enthalpies of a solid-phase transition and fusion for the compound were found by DSC. The obtained results allowed us to calculate thermodynamic properties of crystalline levoglucosan in the temperature range (0 to 384) K. The enthalpy of sublimation for the low-temperature crystal phase was found from the temperature-dependent saturated vapor pressures determined by the Knudsen effusion method. The thermodynamic properties of gaseous levoglucosan were calculated by methods of statistical thermodynamics using the molecular parameters from quantum chemical calculations. The enthalpy of formation of the crystalline compound was found from the experiments in a combustion calorimeter. The gas-phase enthalpy of formation was also obtained at the G4 level of theory. The thermodynamic analysis of equilibria of levoglucosan formation from cellulose, starch, and glucose was conducted.

Fluid Phase Equilibria, Oct 1, 1996

Quasi-isochoric ppT measurements on the vapor of acetic acid were performed in the low-density re... more Quasi-isochoric ppT measurements on the vapor of acetic acid were performed in the low-density region by means of a quartz glass cell of constant volume. Nine isochores extending over the temperature range between 410 and 574 K were measured at densities from 20 up to 51 mol m-3. Including data from literature experimental results are available in the temperature range between 298 and 574 K. Isothermal values needed in the evaluation were calculated in most cases from isochoric or isobaric data by means of a first-order Taylor series, in terms of temperature. The evaluation accounts for the fact that a strong dimerization depending on temperature occurs in acetic acid vapor. An exact statistic-mechanically based equation proposed by Lawson and Dahler as well as by Bich is used. The model considers the equilibrium and the density balance between monomers and dimers as constraints as well as the intermolecular forces between the components of the vapor. The temperature dependence of the dimerization constant and that of the enthalpy of dimerization are deduced for the temperature range between 298 and 500 K.

The Journal of Chemical Thermodynamics, Jul 1, 1997

ABSTRACT

Journal of Chemical & Engineering Data, Feb 25, 2005

ABSTRACT

Molecular Physics, Aug 26, 2014

Journal of Chemical & Engineering Data, Mar 6, 2012

ABSTRACT New, simple, and practical correlations for shear viscosity, self-diffusion coefficient,... more ABSTRACT New, simple, and practical correlations for shear viscosity, self-diffusion coefficient, bulk viscosity, and thermal conductivity of hydrogen sulfide in the limit of zero density are provided, together with a correlation for the second pressure virial coefficient. The correlations are based on the values of thermophysical properties generated from a highly accurate, fully quantum-mechanical, ab initio potential energy surface. The validation of the computed values of thermophysical properties against the rather scarce experimental data demonstrates an excellent agreement with the most accurate data sets. The analysis undertaken indicates that the correlated values provide the most reliable, accurate, and internally consistent representation of thermophysical properties of hydrogen sulfide. The correlations extend over the temperature range (180 to 2000) K. The behavior of each transport property is represented by an independent correlation of the appropriate effective collision cross section as a function of temperature, while the behavior of the second pressure virial coefficient is directly represented as a function of temperature. The uncertainty of the proposed transport property correlations varies from ± 0.4 % for the shear viscosity in the temperature range (300 to 700) K to ± 5.0 % for the bulk viscosity. The uncertainty of the second pressure virial coefficient correlation is estimated to be of the order of ± 1 cm3·mol–1 at temperatures above 400 K, decreasing to ± 30 cm3·mol–1 at 180 K.

High Temperatures-high Pressures, 1999

ABSTRACT

Physical Chemistry Chemical Physics, 2007

Molecular Physics, Dec 10, 2007

A helium-helium interatomic potential energy curve was determined from quantummechanical ab initi... more A helium-helium interatomic potential energy curve was determined from quantummechanical ab initio calculations. Very large atom-centred basis sets including a newly developed d-aug-cc-pV8Z basis set supplemented with bond functions and ab initio methods up to Full CI were applied. The aug-cc-pV7Z basis set of Gdanitz (J. Chem. Phys., 113, 5145 (2000)) was modified to be more consistent with the aug-cc-pV5Z and aug-cc-pV6Z basis sets. The diagonal Born-Oppenheimer corrections as well as corrections for relativistic effects were also calculated. A new analytical representation of the interatomic potential energy was fitted to the ab initio calculated values. In a following paper this potential model will be used in the framework of the quantum-statistical mechanics and of the corresponding kinetic theory to calculate the most important thermophysical properties of helium governed by two-body and three-body interactions.

Journal of Chemical & Engineering Data, Dec 24, 2004

ABSTRACT

Zeitschrift für Physikalische Chemie, Jul 1, 1989

The second cross-virial coefficient B l2 in the system methanol-benzene was calculated for the ra... more The second cross-virial coefficient B l2 in the system methanol-benzene was calculated for the range from 373.15 to 623.15 K by means of combining rules for the (m-6-8)-potential. In one case the parameters of the (m-6-8)-modeI were used for both pure components, in the second case the parameters of the (m-6-8-3)-ansatz were applied for methanol. Furthermore the congruence principle of BRÖNSTED and KOEFOED was tested in calculating the second virial coefficient of equimolar mixtures of methanolbenzene and water-toluene.

Metal Science and Heat Treatment, 1969

ConclusionsSeveral relationships were found between the original aging and the mechanical propert... more ConclusionsSeveral relationships were found between the original aging and the mechanical properties of plates and slabs of alloy AK4-1 in tests of the long-term strength, elongation, and fracture toughness after prolonged holding at 135 and 150°C (below the artificial aging temperature) under tensile stress.Under these conditions the naturally aged slabs and also plates and slabs aged 6, 7, and even 12 h at 190–195°C undergo additional aging consisting of additional decomposition of the solid solution, precipitation of hardening phase, and an increase of the density of the precipitates. As the result of this the long-term strength of the less-aged plates and slabs at testing temperatures of 135 and 150°C exceeds that of the plates and slabs aged at 190–195°C for 12 h, although the long-term ductility is considerably lower.Preliminary holding at 135 and 150°C under tensile stress increases σb and σ0.2. After holding under stresses of 24 and 22.5 kg/mm2 for up to 0.9 of the average time to failure these characteristics remain at their original levels or exceed them. The ductility characteristics (δ and ψ) decrease after holding under stress, particularly for samples aged naturally. The same is true for the fracture toughness and the work of fracture for samples with started cracks. However, with increasing holding time they become almost identical after all aging conditions. The effect of additional aging increases with an increase of the stress during holding.

Chemical Physics, 2012

Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures and... more Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures and of collision-induced light scattering (CILS) at room temperature are computed for gaseous molecular hydrogen using theoretical values for induced dipole moments and pair-polarizability trace and anisotropy as input. Comparison with measured spectra of absorption, isotropic and anisotropic light scattering shows satisfactory agreement, for which the uncertainty in measurement of its spectral moments is seen to be large. Empirical models of the dipole moment and pair-polarizability trace and anisotropy which reproduce the experimental spectra and the first three spectral moments more closely than the fundamental theory are also given. Good agreement between computed and experimental lineshapes of both absorption and scattering is obtained when potential models which are constructed from the thermophysical, transport, total scattering cross-section and spectroscopic properties are used. Also, the use of the new potential in lattice dynamic calculations yields good results for several properties of solid hydrogen.

Journal of Chemical Physics, Aug 28, 2011

An ab initio nonadditive three-body potential for argon has been developed using quantum-chemical... more An ab initio nonadditive three-body potential for argon has been developed using quantum-chemical calculations at the CCSD(T) and CCSDT levels of theory. Applying this potential together with a recent ab initio pair potential from the literature, the third and fourth to seventh pressure virial coefficients of argon were computed by standard numerical integration and the Mayer-sampling Monte Carlo method, respectively, for a wide temperature range. All calculated virial coefficients were fitted separately as polynomials in temperature. The results for the third virial coefficient agree with values evaluated directly from experimental data and with those computed for other nonadditive three-body potentials. We also redetermined the second and third virial coefficients from the best experimental pρT data utilizing the computed higher virial coefficients as constraints. Thus, a significantly closer agreement of the calculated third virial coefficients with the experimental data was achieved. For different orders of the virial expansion, pρT data have been calculated and compared with results from high quality measurements in the gaseous and supercritical region. The theoretically predicted pressures are within the very small experimental errors of ±0.02% for p 12 MPa in the supercritical region near room temperature, whereas for subcritical temperatures the deviations increase up to +0.3%. The computed pressure at the critical density and temperature is about 1.3% below the experimental value. At pressures between 200 MPa and 1000 MPa and at 373 K, the calculated values deviate by 1% to 9% from the experimental results.

Zeitschrift für Physikalische Chemie, 1982

Die Temperaturfunktionen für den zweiten Virialkoeffizienten von Benzen, Toluen, p-Xylen, Fluorbe... more Die Temperaturfunktionen für den zweiten Virialkoeffizienten von Benzen, Toluen, p-Xylen, Fluorbenzen, Chlorbenzen und Phenol werden aus Meßwerten aufgestellt, wobei die gleiche analytische Form für die empirischen Gleichungen gewählt wurde. Die experimentellen Daten werden mit Lennard-Jones-(m-n), (m-6-8)-und (m-6-8-3)-Ansätzen für das intermolekulare Paarpotential ausgewertet. Die Angemessenheit der verwendeten Ansätze bezüglich der Beschreibung von B(T) und die erhaltenen Potentialparameter werden diskutiert.

Zeitschrift für Physikalische Chemie, 1981

Zusammenfassung Der zweite Virialkoeffizient B von Benzoldampf wurde zwischen 75 und 362 °C durch... more Zusammenfassung Der zweite Virialkoeffizient B von Benzoldampf wurde zwischen 75 und 362 °C durch Druckmessung bei konstantem Volumen und bekannter Masse bestimmt. Die sich einstellenden Drücke lagen zwischen 355 und 1507 Torr. Unter Berücksichtigung von Literaturdaten wurde die fl(7>Funktion für den Bereich 30 ... 362 °C aufgestellt. Der Viskositätskoeffizient i) von Benzoldampf wurde zwischen 33 und 355 °C mit einem Schwingscheibenviskosimeter aus Quarzglas gemessen. Der Druck im Viskosimetergefäß lag je nach Meßtemperatur zwischen 70 und 250 Torr. Die t?(7")-Funktion wurde für den angegebenen Temperaturbereich unter Vernachlässigung von Literaturdaten aufgestellt. An der für den zweiten Virialkoeffizienten erhaltenen Temperaturfunktion wurden Ansätze für das intermolekulare Potential aus den Reihen der Lennard-Jones-(6-n)-und-(7-n)-Modelle, an der Temperaturfunktion des Viskositätskoeffizienten wurden Lennard-Jones-(6-n)-Potentiale geprüft. B(T) wird am besten durch einen (7-50)-Ansatz, rj{T) wird am besten durch ein (6-14)-und ein (6-15)-Modell dargestellt. Eine simultane Beschreibung von B(T) und »i(T) mit einem Lennard-Jones-(6-/i)-Potential ist nicht möglich.

The Journal of Chemical Physics, 2021

New interatomic potential energy and interaction-induced polarizability curves for two ground-sta... more New interatomic potential energy and interaction-induced polarizability curves for two ground-state neon atoms were developed and used to predict the second density, acoustic, and dielectric virial coefficients and the dilute gas shear viscosity and thermal conductivity of neon at temperatures up to 5000 K. The potential energy curve is based on supermolecular coupled-cluster (CC) calculations at very high levels up to CC with single, double, triple, quadruple, and perturbative pentuple excitations [CCSDTQ(P)]. Scalar and spin-orbit relativistic effects, the diagonal Born-Oppenheimer correction, and retardation of the dispersion interactions were taken into account. The interaction-induced polarizability curve, which in this work is only needed for the calculation of the second dielectric virial coefficient, is based on supermolecular calculations at levels up to CCSDT and includes a correction for scalar relativistic effects. In addition to these first-principles calculations, highly accurate dielectric-constant gas thermometry (DCGT) datasets measured at temperatures from 24.5 to 200 K were analyzed to obtain the difference between the second density and dielectric virial coefficients with previously unattained accuracy. The agreement of the DCGT values with the ones resulting from the first-principles calculations is, despite some small systematic deviations, very satisfactory. Apart from this combination of two virial coefficients, the calculated thermophysical property values of this work are significantly more accurate than any available experimental data.

High Temperatures-High Pressures, 1999

ABSTRACT

Pure and Applied Chemistry, 2009

Thermodynamic principles can be applied for describing the atmospheres and the internal structure... more Thermodynamic principles can be applied for describing the atmospheres and the internal structure of celestial bodies using Saturn's moon Titan as a most appropriate example. Some basic physical data of Titan such as the measured temperature and pressure on its surface, the atmospheric composition, Titan’s density and diameter, and other information allow us to predict further properties which have not been determined directly by measurements. The existence of a liquid phase covering smaller parts of the surface can be confirmed, and the composition of the liquid can be predicted. The change of temperature with the height over the surface and the appearance of clouds and rainfall in the atmosphere consisting essentially of CH

Zeitschrift für Physikalische Chemie, 1984

Der zweite Virialkoeffizient von Ethanoldampf wurde bestimmt durch Druckmessungen in Abhängigkeit... more Der zweite Virialkoeffizient von Ethanoldampf wurde bestimmt durch Druckmessungen in Abhängigkeit von der Temperatur bei bekanntem konstantem Volumen und gekannter konstanter Masse der Proben. Die erhaltenen Werte sind für den Temperaturbereich 348 ... 573 K tabelliert.

Journal of Molecular Liquids, Nov 1, 2007

The heat capacity of levoglucosan was measured over the temperature range (5 to 370) K by adiabat... more The heat capacity of levoglucosan was measured over the temperature range (5 to 370) K by adiabatic calorimetry. The temperatures and enthalpies of a solid-phase transition and fusion for the compound were found by DSC. The obtained results allowed us to calculate thermodynamic properties of crystalline levoglucosan in the temperature range (0 to 384) K. The enthalpy of sublimation for the low-temperature crystal phase was found from the temperature-dependent saturated vapor pressures determined by the Knudsen effusion method. The thermodynamic properties of gaseous levoglucosan were calculated by methods of statistical thermodynamics using the molecular parameters from quantum chemical calculations. The enthalpy of formation of the crystalline compound was found from the experiments in a combustion calorimeter. The gas-phase enthalpy of formation was also obtained at the G4 level of theory. The thermodynamic analysis of equilibria of levoglucosan formation from cellulose, starch, and glucose was conducted.

Fluid Phase Equilibria, Oct 1, 1996

Quasi-isochoric ppT measurements on the vapor of acetic acid were performed in the low-density re... more Quasi-isochoric ppT measurements on the vapor of acetic acid were performed in the low-density region by means of a quartz glass cell of constant volume. Nine isochores extending over the temperature range between 410 and 574 K were measured at densities from 20 up to 51 mol m-3. Including data from literature experimental results are available in the temperature range between 298 and 574 K. Isothermal values needed in the evaluation were calculated in most cases from isochoric or isobaric data by means of a first-order Taylor series, in terms of temperature. The evaluation accounts for the fact that a strong dimerization depending on temperature occurs in acetic acid vapor. An exact statistic-mechanically based equation proposed by Lawson and Dahler as well as by Bich is used. The model considers the equilibrium and the density balance between monomers and dimers as constraints as well as the intermolecular forces between the components of the vapor. The temperature dependence of the dimerization constant and that of the enthalpy of dimerization are deduced for the temperature range between 298 and 500 K.

The Journal of Chemical Thermodynamics, Jul 1, 1997

ABSTRACT

Journal of Chemical & Engineering Data, Feb 25, 2005

ABSTRACT

Molecular Physics, Aug 26, 2014

Journal of Chemical & Engineering Data, Mar 6, 2012

ABSTRACT New, simple, and practical correlations for shear viscosity, self-diffusion coefficient,... more ABSTRACT New, simple, and practical correlations for shear viscosity, self-diffusion coefficient, bulk viscosity, and thermal conductivity of hydrogen sulfide in the limit of zero density are provided, together with a correlation for the second pressure virial coefficient. The correlations are based on the values of thermophysical properties generated from a highly accurate, fully quantum-mechanical, ab initio potential energy surface. The validation of the computed values of thermophysical properties against the rather scarce experimental data demonstrates an excellent agreement with the most accurate data sets. The analysis undertaken indicates that the correlated values provide the most reliable, accurate, and internally consistent representation of thermophysical properties of hydrogen sulfide. The correlations extend over the temperature range (180 to 2000) K. The behavior of each transport property is represented by an independent correlation of the appropriate effective collision cross section as a function of temperature, while the behavior of the second pressure virial coefficient is directly represented as a function of temperature. The uncertainty of the proposed transport property correlations varies from ± 0.4 % for the shear viscosity in the temperature range (300 to 700) K to ± 5.0 % for the bulk viscosity. The uncertainty of the second pressure virial coefficient correlation is estimated to be of the order of ± 1 cm3·mol–1 at temperatures above 400 K, decreasing to ± 30 cm3·mol–1 at 180 K.

High Temperatures-high Pressures, 1999

ABSTRACT

Physical Chemistry Chemical Physics, 2007

Molecular Physics, Dec 10, 2007

A helium-helium interatomic potential energy curve was determined from quantummechanical ab initi... more A helium-helium interatomic potential energy curve was determined from quantummechanical ab initio calculations. Very large atom-centred basis sets including a newly developed d-aug-cc-pV8Z basis set supplemented with bond functions and ab initio methods up to Full CI were applied. The aug-cc-pV7Z basis set of Gdanitz (J. Chem. Phys., 113, 5145 (2000)) was modified to be more consistent with the aug-cc-pV5Z and aug-cc-pV6Z basis sets. The diagonal Born-Oppenheimer corrections as well as corrections for relativistic effects were also calculated. A new analytical representation of the interatomic potential energy was fitted to the ab initio calculated values. In a following paper this potential model will be used in the framework of the quantum-statistical mechanics and of the corresponding kinetic theory to calculate the most important thermophysical properties of helium governed by two-body and three-body interactions.

Journal of Chemical & Engineering Data, Dec 24, 2004

ABSTRACT

Zeitschrift für Physikalische Chemie, Jul 1, 1989

The second cross-virial coefficient B l2 in the system methanol-benzene was calculated for the ra... more The second cross-virial coefficient B l2 in the system methanol-benzene was calculated for the range from 373.15 to 623.15 K by means of combining rules for the (m-6-8)-potential. In one case the parameters of the (m-6-8)-modeI were used for both pure components, in the second case the parameters of the (m-6-8-3)-ansatz were applied for methanol. Furthermore the congruence principle of BRÖNSTED and KOEFOED was tested in calculating the second virial coefficient of equimolar mixtures of methanolbenzene and water-toluene.

Metal Science and Heat Treatment, 1969

ConclusionsSeveral relationships were found between the original aging and the mechanical propert... more ConclusionsSeveral relationships were found between the original aging and the mechanical properties of plates and slabs of alloy AK4-1 in tests of the long-term strength, elongation, and fracture toughness after prolonged holding at 135 and 150°C (below the artificial aging temperature) under tensile stress.Under these conditions the naturally aged slabs and also plates and slabs aged 6, 7, and even 12 h at 190–195°C undergo additional aging consisting of additional decomposition of the solid solution, precipitation of hardening phase, and an increase of the density of the precipitates. As the result of this the long-term strength of the less-aged plates and slabs at testing temperatures of 135 and 150°C exceeds that of the plates and slabs aged at 190–195°C for 12 h, although the long-term ductility is considerably lower.Preliminary holding at 135 and 150°C under tensile stress increases σb and σ0.2. After holding under stresses of 24 and 22.5 kg/mm2 for up to 0.9 of the average time to failure these characteristics remain at their original levels or exceed them. The ductility characteristics (δ and ψ) decrease after holding under stress, particularly for samples aged naturally. The same is true for the fracture toughness and the work of fracture for samples with started cracks. However, with increasing holding time they become almost identical after all aging conditions. The effect of additional aging increases with an increase of the stress during holding.

Chemical Physics, 2012

Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures and... more Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures and of collision-induced light scattering (CILS) at room temperature are computed for gaseous molecular hydrogen using theoretical values for induced dipole moments and pair-polarizability trace and anisotropy as input. Comparison with measured spectra of absorption, isotropic and anisotropic light scattering shows satisfactory agreement, for which the uncertainty in measurement of its spectral moments is seen to be large. Empirical models of the dipole moment and pair-polarizability trace and anisotropy which reproduce the experimental spectra and the first three spectral moments more closely than the fundamental theory are also given. Good agreement between computed and experimental lineshapes of both absorption and scattering is obtained when potential models which are constructed from the thermophysical, transport, total scattering cross-section and spectroscopic properties are used. Also, the use of the new potential in lattice dynamic calculations yields good results for several properties of solid hydrogen.

Journal of Chemical Physics, Aug 28, 2011

An ab initio nonadditive three-body potential for argon has been developed using quantum-chemical... more An ab initio nonadditive three-body potential for argon has been developed using quantum-chemical calculations at the CCSD(T) and CCSDT levels of theory. Applying this potential together with a recent ab initio pair potential from the literature, the third and fourth to seventh pressure virial coefficients of argon were computed by standard numerical integration and the Mayer-sampling Monte Carlo method, respectively, for a wide temperature range. All calculated virial coefficients were fitted separately as polynomials in temperature. The results for the third virial coefficient agree with values evaluated directly from experimental data and with those computed for other nonadditive three-body potentials. We also redetermined the second and third virial coefficients from the best experimental pρT data utilizing the computed higher virial coefficients as constraints. Thus, a significantly closer agreement of the calculated third virial coefficients with the experimental data was achieved. For different orders of the virial expansion, pρT data have been calculated and compared with results from high quality measurements in the gaseous and supercritical region. The theoretically predicted pressures are within the very small experimental errors of ±0.02% for p 12 MPa in the supercritical region near room temperature, whereas for subcritical temperatures the deviations increase up to +0.3%. The computed pressure at the critical density and temperature is about 1.3% below the experimental value. At pressures between 200 MPa and 1000 MPa and at 373 K, the calculated values deviate by 1% to 9% from the experimental results.

Zeitschrift für Physikalische Chemie, 1982

Die Temperaturfunktionen für den zweiten Virialkoeffizienten von Benzen, Toluen, p-Xylen, Fluorbe... more Die Temperaturfunktionen für den zweiten Virialkoeffizienten von Benzen, Toluen, p-Xylen, Fluorbenzen, Chlorbenzen und Phenol werden aus Meßwerten aufgestellt, wobei die gleiche analytische Form für die empirischen Gleichungen gewählt wurde. Die experimentellen Daten werden mit Lennard-Jones-(m-n), (m-6-8)-und (m-6-8-3)-Ansätzen für das intermolekulare Paarpotential ausgewertet. Die Angemessenheit der verwendeten Ansätze bezüglich der Beschreibung von B(T) und die erhaltenen Potentialparameter werden diskutiert.

Zeitschrift für Physikalische Chemie, 1981

Zusammenfassung Der zweite Virialkoeffizient B von Benzoldampf wurde zwischen 75 und 362 °C durch... more Zusammenfassung Der zweite Virialkoeffizient B von Benzoldampf wurde zwischen 75 und 362 °C durch Druckmessung bei konstantem Volumen und bekannter Masse bestimmt. Die sich einstellenden Drücke lagen zwischen 355 und 1507 Torr. Unter Berücksichtigung von Literaturdaten wurde die fl(7>Funktion für den Bereich 30 ... 362 °C aufgestellt. Der Viskositätskoeffizient i) von Benzoldampf wurde zwischen 33 und 355 °C mit einem Schwingscheibenviskosimeter aus Quarzglas gemessen. Der Druck im Viskosimetergefäß lag je nach Meßtemperatur zwischen 70 und 250 Torr. Die t?(7")-Funktion wurde für den angegebenen Temperaturbereich unter Vernachlässigung von Literaturdaten aufgestellt. An der für den zweiten Virialkoeffizienten erhaltenen Temperaturfunktion wurden Ansätze für das intermolekulare Potential aus den Reihen der Lennard-Jones-(6-n)-und-(7-n)-Modelle, an der Temperaturfunktion des Viskositätskoeffizienten wurden Lennard-Jones-(6-n)-Potentiale geprüft. B(T) wird am besten durch einen (7-50)-Ansatz, rj{T) wird am besten durch ein (6-14)-und ein (6-15)-Modell dargestellt. Eine simultane Beschreibung von B(T) und »i(T) mit einem Lennard-Jones-(6-/i)-Potential ist nicht möglich.

The Journal of Chemical Physics, 2021

New interatomic potential energy and interaction-induced polarizability curves for two ground-sta... more New interatomic potential energy and interaction-induced polarizability curves for two ground-state neon atoms were developed and used to predict the second density, acoustic, and dielectric virial coefficients and the dilute gas shear viscosity and thermal conductivity of neon at temperatures up to 5000 K. The potential energy curve is based on supermolecular coupled-cluster (CC) calculations at very high levels up to CC with single, double, triple, quadruple, and perturbative pentuple excitations [CCSDTQ(P)]. Scalar and spin-orbit relativistic effects, the diagonal Born-Oppenheimer correction, and retardation of the dispersion interactions were taken into account. The interaction-induced polarizability curve, which in this work is only needed for the calculation of the second dielectric virial coefficient, is based on supermolecular calculations at levels up to CCSDT and includes a correction for scalar relativistic effects. In addition to these first-principles calculations, highly accurate dielectric-constant gas thermometry (DCGT) datasets measured at temperatures from 24.5 to 200 K were analyzed to obtain the difference between the second density and dielectric virial coefficients with previously unattained accuracy. The agreement of the DCGT values with the ones resulting from the first-principles calculations is, despite some small systematic deviations, very satisfactory. Apart from this combination of two virial coefficients, the calculated thermophysical property values of this work are significantly more accurate than any available experimental data.

High Temperatures-High Pressures, 1999

ABSTRACT

Pure and Applied Chemistry, 2009

Thermodynamic principles can be applied for describing the atmospheres and the internal structure... more Thermodynamic principles can be applied for describing the atmospheres and the internal structure of celestial bodies using Saturn's moon Titan as a most appropriate example. Some basic physical data of Titan such as the measured temperature and pressure on its surface, the atmospheric composition, Titan’s density and diameter, and other information allow us to predict further properties which have not been determined directly by measurements. The existence of a liquid phase covering smaller parts of the surface can be confirmed, and the composition of the liquid can be predicted. The change of temperature with the height over the surface and the appearance of clouds and rainfall in the atmosphere consisting essentially of CH