A surface-hopping method for semiclassical calculations of cross sections for radiative association with electronic transitions

Szabó, Péter; Gustafsson, Magnus

doi:10.1063/1.5000573

Cited by 11 publications

(7 citation statements)

References 64 publications

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“…The calculation of reaction rate constants for other radiative association reactions and the development of the methods to conduct these calculations has continued in the research group, and among collaborators, of the author since the publication of paper I. [106][107][108][109][110][111][112][113][114] One of the main directions that further research is going toward is the calculation of radiative association rate constants for systems larger than diatoms. As radiative association generally becomes more likely the larger the molecule, due to a more long lived activated complex, as explained e.g.…”

Section: Resultsmentioning

confidence: 99%

Classical Wigner model based on a Feynman path integral open polymer

Svensson

Poulsen

Nyman

2020

The Journal of Chemical Physics

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When using mathematical models to computationally investigate a chemical system it is important that the methods used are accurate enough to account for the relevant properties of the system and at the same time simple enough to be computationally affordable. This thesis presents research that so far has resulted in three published papers and one unpublished manuscript. It concerns the application and development of computational methods for chemistry, with some extra emphasis on the calculation of reaction rate constants. In astrochemistry radiative association is a relevant reaction mechanism for the formation of molecules. The rate constants for such reactions are often difficult to obtain though experiments. In the first published paper of the thesis a rate constant for the formation of the hydroxyl radical, through the radiative association of atomic oxygen and hydrogen, is presented. This rate constant was calculated by a combination of different methods and should be an improvement over previously available rate constants. In the the second published paper of this thesis two kinds of basis functions, for use with a variational principle for the dynamics of quantum distributions in phase space, i.e. Wigner functions, is presented. These are tested on model systems and found to have some appealing properties. The classical Wigner method is an approximate method of simulation, where an initial quantum distribution is propagated in time with classical mechanics. In the third published paper of this thesis a new method of sampling the initial quantum distribution, with an imaginary time Feynman path integral, is derived and tested on model systems. In the unpublished manuscript, this new method is applied to reaction rate constants and tested on two model sysv Abstract tems. The new sampling method shows some promise for future applications. vi Preface You have guessed right; I have lately been so deeply engaged in one occupation that I have not allowed myself sufficient rest, as you see: but I hope, I sincerely hope, that all these employments are now at an end, and that I am at length free.

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Section: Resultsmentioning

confidence: 99%

Classical Wigner model based on a Feynman path integral open polymer

Svensson

Poulsen

Nyman

2020

The Journal of Chemical Physics

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“…The random sampling of the initial conditions is the same as we did it in the Method I. However, in the second MC layer we introduce another random sampling that is mimicking the quantized nature of the radiation similarly to our recently established surface-hopping formalism 55 that is used for the description of radiative association with electronic transitions. In this second MC sampling we decide randomly about the fate of trajectories whether happened photon emission during a collision or not.…”

Section: Methods Ii: Discrete Photonsmentioning

confidence: 99%

“…To improve the efficiency of the MC formula we are adapting the MC procedure developed originally for the surface-hopping method for radiative association 55 . To this end we use the fact that the classical Larmor formula can be considered as the classical limit of the Fermi's golden rule (FGR) 59 .…”

Section: Methods Ii: Discrete Photonsmentioning

confidence: 99%

“…Two trajectory-based classical methods have been recently established for RA. One is for RA in absence of electronic transitions based on the classical Larmor theory of radiation 54 , and another for the calculation of RA through electronic transitions based on the semiclassical surface-hopping formalism 55 .…”

Section: Fig 1 Schematic Representation Of H + Cn Potential Energy Su...mentioning

confidence: 99%

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Polyatomic radiative association by quasiclassical trajectory calculations: Cross section for the formation of HCN molecules in H + CN collisions

Szabó¹,

Gustafsson²

2021

Preprint

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We have developed the polyatomic extension of a recently established (M. Gustafsson, J. Chem. Phys, 138, 074308 ( 2013)) classical theory of radiative association in the absence of electronic transitions. The cross section of the process is calculated by a quasiclassical trajectory method combined with the classical Larmor formula which can provide the radiated power in collisions. We have also proposed a double-layered Monte Carlo scheme for efficient computation of ro-vibrationally quantum state resolved cross sections for radiative association. Besides the method development, we also calculated and fitted the global potential energy and dipole surface for the H + CN collisions to test our polyatomic semiclassical method.

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“…The rate coefficients and cross sections for several diatomic molecules with radiative stabilization mechanism have been calculated in the last 20 years with high-level quantum dynamical and semiclassical methods (Singh and Andreazza, 2000;Barinovs and van Hemert, 2006;Antipov et al, 2009;Franz et al, 2011;Andreazza et al, 2012;Andreazza and de Almeida, 2014;Gustafsson et al, 2014;Nyman et al, 2015;Andreazza et al, 2016;Babb and McLaughlin, 2017;Kathir et al, 2017;Szabó and Gustafsson, 2017;Andreazza et al, 2018;Forrey et al, 2018;Szabó and Gustafsson, 2018;Babb et al, 2019a;Babb et al, 2019b;Gustafsson and Forrey, 2019;Zamecnikova et al, 2019;Zamecnikova et al, 2020;Bai et al, 2021). The formation of BeH + molecule through radiative association has not been studied yet.…”

Section: Introductionmentioning

confidence: 99%

Formation of the BeH+ and BeD+ Molecules in Be+ + H/D Collisions Through Radiative Association

Szabó

Góger

Gustafsson

2021

Front. Astron. Space Sci.

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Cross sections and rate coefficients for the formation of BeH+ and BeD+ molecules in Be+ + H/D collisions through radiative association are calculated using quantum mechanical perturbation theory and Breit-Wigner theory. The local thermodynamic equilibrium limit of the molecule formation is also studied, since the process is also relevant in environments with high-density and/or strong radiation fields. The obtained rate coefficients may facilitate the kinetic modelling of BeH+/BeD+ production in astrochemical environments as well as the corrosion chemistry of thermonuclear fusion reactors.

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A surface-hopping method for semiclassical calculations of cross sections for radiative association with electronic transitions

Cited by 11 publications

References 64 publications

Classical Wigner model based on a Feynman path integral open polymer

Classical Wigner model based on a Feynman path integral open polymer

Polyatomic radiative association by quasiclassical trajectory calculations: Cross section for the formation of HCN molecules in H + CN collisions

Formation of the BeH+ and BeD+ Molecules in Be+ + H/D Collisions Through Radiative Association

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