Bimolecular rate, rotational relaxation and transport coefficients for gaseous hydrogen fluoride

“…In order to obtain the value it is necessary to carry out extensive QM calculations. 45 We used the form of nitrogen-nitrogen interaction potential specified by AWJ ͑Ref. In a series of papers, 17,28,38 they reported intensive Hartree-Fock LCAO-MO QM calculations.…”

Section: N 2 -N 2 Interactionmentioning

confidence: 99%

Equation of state of nitrogen (N2) at high pressures and high temperatures: Molecular dynamics simulation

Krukowski

Strąk

2006

The Journal of Chemical Physics

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Nitrogen equation of state at pressures up to 30 GPa (300 kbars) and temperatures above 800 K was studied by molecular dynamics (MD) simulations. The dynamics of the N(2) molecules is treated in hard rotor approximation, i.e., it accounts both translational and rotational degrees of freedom. The rotational motion of the N(2) molecule is treated assuming constant moment of inertia of the nitrogen molecule. The new MD program fully accounts anisotropic molecular nitrogen interaction. The N(2)-N(2) interaction potential has been derived by van der Avoird et al. [J. Chem. Phys. 84, 1629 (1986)] using the results of high precision Hartree-Fock ab initio quantum mechanical calculations. The potential, fully accounts rotational symmetry of the N(2)-N(2) system, by employing 6-j Wigner symbols, i.e., preserving full rotational symmetry of the system. Various numerical algorithms were tested, in order to achieve the energy preservation during the simulation. It has been demonstrated that the standard Verlet algorithm was not preserving the energy for the standard MD time step, equal to 5x10(-16) s. Runge-Kutta fourth order method was able to preserve the energy within 10(-4) relative error, but it requires calculation of the force four times for each time step and therefore it is highly inefficient. A predictor-corrector method of the fifth order (PC5) was found to be efficient and precise and was therefore adopted for the simulation of the molecular nitrogen properties at high pressure. Singer and Fincham algorithms were tested and were found to be as precise as PC5 algorithm and they were also used in the simulation of the equation of state. Results of MD simulations are in very good agreement with the experimental data on nitrogen equation of state at pressures below 1 GPa (10 kbars). For higher pressures, up to 30 GPa (300 kbars), i.e., close to molecular nitrogen stability limit, determined by Nellis et al. [Phys. Rev. Lett. 85, 1262 (1984)], the obtained numerical results provide new data of the experimentally unexplored region. These data were formulated in the analytical form of pressure-density-temperature equation of state.

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“…Due to that only this mechanism will be discussed here, where the consideration mainly will be based on Bunker's early work [5], on the resonance complex theory of Whitlock et al [6], and on the classical trajectory method discussed by us some years ago [7]. Of these only the energy transfer mechanism can show 'fall-off' behaviour, as it will be discussed in chapter 3.…”

Section: Low Pressure Termolecular Kineticsmentioning

confidence: 99%

“…Calculations of rate coefficients like k 4 have been reported by several groups, for instance in Ref. [7] K 3 can also be obtained as the average lifetime for the collision complexes. [8] for some reactions of the type Si ϩ Si ϩ M → Si 2 ϩ M. Calculation procedures were suggested early for the pseudo equilibrium constant K 3 [9].…”

Section: Low Pressure Termolecular Kineticsmentioning

confidence: 99%

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Collision Model of `Fall-Off´ in Recombination Reactions

Nyeland¹

2000

Zeitschrift Für Physikalische Chemie

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Assuming random, multiple collisions the 'fall-off' problem in chemical recombination reactions is reconsidered. Following this approximative model the 'fall-off' from third order reactions at low pressure to second order reactions at high pressure appears in a simple way as a consequence of the collision time considered as the lifetime of the unstable van der Waals complex formed initially in the recombination mechanism.Comparisons are presented for results from the 'fall-off' following the Lindemann type mechanism, and of the method of Troe, Gilbert et al. based on the RRKM theory, together with some experimental results for recombination reactions at low and intermediate pressures. *

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Bimolecular rate, rotational relaxation and transport coefficients for gaseous hydrogen fluoride

Cited by 15 publications

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Rotational relaxation and transport properties of oxygen by using the importance sampling method

Rotational relaxation and transport properties of oxygen by using the importance sampling method

Equation of state of nitrogen (N2) at high pressures and high temperatures: Molecular dynamics simulation

Collision Model of `Fall-Off´ in Recombination Reactions

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