Dear all,
I am currently modeling the plasma kinetics in pure CO2 plasmas with a large focus on vibrational kinetics. The plan is to optimize the vibrational kinetics (VV and VT transfer), if possible, using rate constants which are calculated using quantum mechanical or semiclassical methods, especially near the dissociation limit. The question is whether accurate (enough) methods/codes exist and if they are cost efficient?
Best Regards and looking forward for your answers,
Stijn
Dear Markus, I read this very good work carefully and I am very grateful for your answer. This paper, however, also stresses the need for more accurate data involving molecule-molecule cross sections and/or rate constants. So, indeed the question remains.
Best regards and thank you,
Stijn
Mr. Heijkers,
Such as computations you can perform by Gaussian (www.Gaussian.com).
You can perform harmonic and anharmonic analysis, along with the hindered internal rotor analysis for treatment of anharmonic motions (if you can apply it, but for a large set models most probably yes); including using various isotopes. Despite the fact that collision processes are described as irreversible ones and presumably cannot be interpreted in terms of Boltzmann distribution of the internal energy, there is shown that in many CID reactions, for example, it is applicable to non-Boltzmann cases as well. In this context, please pay attention to refs. 1-3. Given that, obtaining information about the internal energy you can predict rate constants of collision processes.
You can perform transition state analysis, as well as, accounting for the stable intermediates. Their properties can be computed as well as. And ab initio molecular dynamics you can carry out using ADMP as well. Nevertheless, you have collision process, there is an interesting MD profile for your system 2CO2 (attachment, rigid rotor approximation). The minimum corresponds to a frontal interaction O=C=O...O=C=O. Such state can be included as a high probable one, interacting modes studying a collison process. If a frexibil CO2 molecule skeleton due to collision is taken into account, then the potential energy picture is more complex, but as computational cost, not so expensive. There are possible many sates, but not all should be stable from a thermodynamics viewpoint.
You can use a large set theoretical methods, under various conditions, so the abilities for theoretical modeling are very, very large.
The question, is rather have you available Gaussian? If not, then which program package/s have you available?
There would be better to pay attention to the Gaussian's online manual:
[Ref. 1] R. Cooks, P. Wong, Kinetic Method of Making Thermochemical Determinations: Advances and Applications, Accts. Chem. Res. 31,1998, 739-786.
[Ref. 2] R.Cooks, J. Koskinen, P.Thomas, The Kinetic Method of Making Thermochemical Determinations, J. Mass Spectrom. 34, 85-92 (1999)
[Ref. 3] R.Cookst, J. Patrickt, T. Kotiaho, S. McLuckeyn, Thermochemical determination by the kinetic method, Mass Spectrom. Rev, 1994, 13, 287-339.
Dear dr. Ivanova,
Thank you for your thorough answer. I will read this information and the Gaussian manual (more) carefully. Although Gaussian is not yet available in our group, our university has a license so that won't be a big issue to get it installed. This may sound as a stupid question, since I am new in this field, but are there works where state to state rate constants for vibrational energy transfer in polyatomic molecules such as CO2 are calculated using Gaussian? During my search, I couldn't find any (yet).
Best Regards,
Stijn
Dear Stijn Heijkers ,
My favorite method is the Quasiclassical Trajectory method. With a QCT code state-to-state crossections and thermal rate constants can be obtained....and for such a big system the QCT method is the best choice.
I work with my own developed QCT code, but you can use free codes like VENUS96 (developed by W. L. Hase)
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