Statistical thermodynamic description of H2 molecules in normal ortho/para mixture

Colonna, G.; D’Angola, A.; Capitelli, M.

doi:10.1016/j.ijhydene.2012.03.103

Cited by 16 publications

(42 citation statements)

References 29 publications

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“…In addition to equilibrium hydrogen, we also calculate the normal hydrogen following the paradigm of Colonna et al (2012). In this case, ortho-hydrogen and para-hydrogen are not in equilibrium, but act as separate species.…”

Section: Orto/para Ratio Of Molecular Hydrogenmentioning

confidence: 99%

“…The partition function for ortho-hydrogen is (as opposed to Q para ) referred to the first excited rotational level (J = 1) of the ground electronic state in its ground vibrational level. ε 001 can be considered as the formation energy of the ortho-hydrogen Colonna et al (2012). Q int is then Colonna et al (2012) …”

Section: Orto/para Ratio Of Molecular Hydrogenmentioning

confidence: 99%

“…ε 001 can be considered as the formation energy of the ortho-hydrogen Colonna et al (2012). Q int is then Colonna et al (2012) …”

Section: Orto/para Ratio Of Molecular Hydrogenmentioning

confidence: 99%

“…The authors determined the internal partition function for normal hydrogen on a rigorous basis, solving the existing ambiguity in the definition of those quantities directly related to partition functions rather than on its derivatives Colonna et al (2012). The authors used case 7 with more molecular constants for the ground and first few electronically excited states than shown with Eqs.…”

Section: Colonna Et Al (2012 C2012mentioning

confidence: 99%

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Partition functions

Popovas

Jørgensen

2016

A&A

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Context. Hydrogen is the most abundant molecule in the Universe. Its thermodynamic quantities dominate the physical conditions in molecular clouds, protoplanetary disks, etc. It is also of high interest in plasma physics. Therefore thermodynamic data for molecular hydrogen have to be as accurate as possible in a wide temperature range. Aims. We here rigorously show the shortcomings of various simplifications that are used to calculate the total internal partition function. These shortcomings can lead to errors of up to 40 percent or more in the estimated partition function. These errors carry on to calculations of thermodynamic quantities. Therefore a more complicated approach has to be taken. Methods. Seven possible simplifications of various complexity are described, together with advantages and disadvantages of direct summation of experimental values. These were compared to what we consider the most accurate and most complete treatment (case 8). Dunham coefficients were determined from experimental and theoretical energy levels of a number of electronically excited states of H 2 . Both equilibrium and normal hydrogen was taken into consideration. Results. Various shortcomings in existing calculations are demonstrated, and the reasons for them are explained. New partition functions for equilibrium, normal, and ortho and para hydrogen are calculated and thermodynamic quantities are reported for the temperature range 1-20 000 K. Our results are compared to previous estimates in the literature. The calculations are not limited to the ground electronic state, but include all bound and quasi-bound levels of excited electronic states. Dunham coefficients of these states of H 2 are also reported. Conclusions. For most of the relevant astrophysical cases it is strongly advised to avoid using simplifications, such as a harmonic oscillator and rigid rotor or ad hoc summation limits of the eigenstates to estimate accurate partition functions and to be particularly careful when using polynomial fits to the computed values. Reported internal partition functions and thermodynamic quantities in the present work are shown to be more accurate than previously available data.

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Section: Orto/para Ratio Of Molecular Hydrogenmentioning

confidence: 99%

Section: Orto/para Ratio Of Molecular Hydrogenmentioning

confidence: 99%

“…ε 001 can be considered as the formation energy of the ortho-hydrogen Colonna et al (2012). Q int is then Colonna et al (2012) …”

Section: Orto/para Ratio Of Molecular Hydrogenmentioning

confidence: 99%

Section: Colonna Et Al (2012 C2012mentioning

confidence: 99%

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Partition functions

Popovas

Jørgensen

2016

A&A

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“…For atoms the internal contribution is often neglected, except in some cases, when low lying states are considered. These assumptions are valid in a limited range of temperature [79], moreover quantum effects as well as ortho-para separation [80] is not considered. For atomic and atomic ion species also the contribution of the cutoff should be considered and the number of levels entering in the partition function depends on the gas density and plasma composition [79].…”

Section: Thermodynamic and Transport Propertiesmentioning

confidence: 99%

Problems and perspectives of state-to-state kinetics for high enthalpy plasma flows (Invited)

Colonna

2014

AIP Conference Proceedings

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State-to-state kinetic description of non-equilibrium radiative gas flow AIP Conf.Abstract. The paper will present a brief overview of the applications of state-to-state kinetics in modeling fluid dynamics. The research activities ranges from hypersonic entry (boundary layer, shock wave) to ground test facilities, from MHD interaction to DBD flow control. The state-to-state model in fluid dynamics in the last years is rapidly diffusing, promising new interesting developments in the next future.

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Dynamics of Hydrogen in Silicon at Finite Temperatures from First Principles

Gomes

Markevich

Peaker

et al. 2022

Physica Status Solidi (b)

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Hydrogen defects in silicon still hold unsolved problems, whose disclosure is fundamental for future advances in Si technologies. Among the open issues is the mechanism for the condensation of atomic hydrogen into molecules in Si quenched from above T≈700 °C to room temperature. Based on first‐principles calculations, the thermodynamics of hydrogen monomers and dimers is investigated at finite temperatures within the harmonic approximation. Free energies of formation indicate that the population of normalH− cannot be neglected when compared to that of normalH+ at high temperatures. The results allow us to propose that molecular formation occurs during cooling processes, in the temperature window T≈700−500 K, above which the molecules collide with Si—Si bonds and dissociate, and below which the fraction of normalH− becomes negligible. The formation of normalH− and most notably of a fast‐diffusing neutral species can also provide an explanation for the apparent accelerated diffusivity of atomic hydrogen at elevated temperatures in comparison to the figures extrapolated from measurements carried out at cryogenic temperatures. Finally, it is shown that the observed diffusivity of molecules is better described upon the assumption that they are nearly free rotors, all along the migration path, including at the transition state.

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Statistical thermodynamic description of H2 molecules in normal ortho/para mixture

Cited by 16 publications

References 29 publications

Partition functions

Partition functions

Problems and perspectives of state-to-state kinetics for high enthalpy plasma flows (Invited)

Dynamics of Hydrogen in Silicon at Finite Temperatures from First Principles

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