State-to-state rotational transitions in H 2+H 2 collisions at low temperatures

Teck Ghee Lee; N. Balakrishnan; R. C. Forrey; P. C. Stancil; D. R. Schultz; Gary J. Ferland

doi:10.1063/1.2338319

State-to-state rotational transitions in H ₂+H ₂ collisions at low temperatures

Teck Ghee Lee, N. Balakrishnan, R. C. Forrey, P. C. Stancil, D. R. Schultz, Gary J. Ferland

Physics And Astronomy

Research output: Contribution to journal › Article › peer-review

45 Scopus citations

Abstract

We present quantum mechanical close-coupling calculations of collisions between two hydrogen molecules over a wide range of energies, extending from the ultracold limit to the superthermal region. The two most recently published potential energy surfaces for the H ₂-H ₂ complex, the so-called Diep-Johnson (DJ) [J. Chem. Phys. 112, 4465 (2000); 113, 3480 (2000)] and Boothroyd-Martin-Keogh-Peterson (BMKP) [J. Chem. Phys. 116, 666 (2002)] surfaces, are quantitatively evaluated and compared through the investigation of rotational transitions in H ₂ +H ₂ collisions within rigid rotor approximation. The BMKP surface is expected to be an improvement, approaching chemical accuracy, over all conformations of the potential energy surface compared to previous calculations of H ₂-H ₂ interaction. We found significant differences in rotational excitation/deexcitation cross sections computed on the two surfaces in collisions between two para-H ₂ molecules. The discrepancy persists over a large range of energies from the ultracold regime to thermal energies and occurs for several low-lying initial rotational levels. Good agreement is found with experiment B. Maté et al., [J. Chem. Phys. 122, 064313 (2005)] for the lowest rotational excitation process, but only with the use of the DJ potential. Rate coefficients computed with the BMKP potential are an order of magnitude smaller.

Original language	English
Article number	114302
Journal	Journal of Chemical Physics
Volume	125
Issue number	11
DOIs	https://doi.org/10.1063/1.2338319
State	Published - 2006

Bibliographical note

Funding Information:
Two of the authors (T.G.L. and G.J.F.) acknowledge support from NASA Grant No. NNG05GD81G and the Spitzer Space Telescope Theoretical Research Program. The work of one of the authors (R.C.F.) was supported by NSF Grant Nos. PHY-0244066 and PHY-0554794. Another author (N.B.) acknowledges support from NSF Grant No. PHY-0555565 and DOE Grant No. DE-FG36-05GO85028. One of the authors (P.C.S.) acknowledges support from NSF Grant No. AST-0087172. The authors acknowledge support from the Institute for Theoretical Atomic, Molecular, and Optical Physics at the Harvard-Smithsonian Center for Astrophysics for a workshop which initiated this work.

ASJC Scopus subject areas

Physics and Astronomy (all)
Physical and Theoretical Chemistry

Access to Document

10.1063/1.2338319

Cite this

@article{43ed3ace92f143e38adcc92ac68de05b,

title = "State-to-state rotational transitions in H 2+H 2 collisions at low temperatures",

abstract = "We present quantum mechanical close-coupling calculations of collisions between two hydrogen molecules over a wide range of energies, extending from the ultracold limit to the superthermal region. The two most recently published potential energy surfaces for the H 2-H 2 complex, the so-called Diep-Johnson (DJ) [J. Chem. Phys. 112, 4465 (2000); 113, 3480 (2000)] and Boothroyd-Martin-Keogh-Peterson (BMKP) [J. Chem. Phys. 116, 666 (2002)] surfaces, are quantitatively evaluated and compared through the investigation of rotational transitions in H 2 +H 2 collisions within rigid rotor approximation. The BMKP surface is expected to be an improvement, approaching chemical accuracy, over all conformations of the potential energy surface compared to previous calculations of H 2-H 2 interaction. We found significant differences in rotational excitation/deexcitation cross sections computed on the two surfaces in collisions between two para-H 2 molecules. The discrepancy persists over a large range of energies from the ultracold regime to thermal energies and occurs for several low-lying initial rotational levels. Good agreement is found with experiment B. Mat{\'e} et al., [J. Chem. Phys. 122, 064313 (2005)] for the lowest rotational excitation process, but only with the use of the DJ potential. Rate coefficients computed with the BMKP potential are an order of magnitude smaller.",

author = "Lee, {Teck Ghee} and N. Balakrishnan and Forrey, {R. C.} and Stancil, {P. C.} and Schultz, {D. R.} and Ferland, {Gary J.}",

note = "Funding Information: Two of the authors (T.G.L. and G.J.F.) acknowledge support from NASA Grant No. NNG05GD81G and the Spitzer Space Telescope Theoretical Research Program. The work of one of the authors (R.C.F.) was supported by NSF Grant Nos. PHY-0244066 and PHY-0554794. Another author (N.B.) acknowledges support from NSF Grant No. PHY-0555565 and DOE Grant No. DE-FG36-05GO85028. One of the authors (P.C.S.) acknowledges support from NSF Grant No. AST-0087172. The authors acknowledge support from the Institute for Theoretical Atomic, Molecular, and Optical Physics at the Harvard-Smithsonian Center for Astrophysics for a workshop which initiated this work.",

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T1 - State-to-state rotational transitions in H 2+H 2 collisions at low temperatures

AU - Lee, Teck Ghee

AU - Balakrishnan, N.

AU - Forrey, R. C.

AU - Stancil, P. C.

AU - Schultz, D. R.

AU - Ferland, Gary J.

N1 - Funding Information: Two of the authors (T.G.L. and G.J.F.) acknowledge support from NASA Grant No. NNG05GD81G and the Spitzer Space Telescope Theoretical Research Program. The work of one of the authors (R.C.F.) was supported by NSF Grant Nos. PHY-0244066 and PHY-0554794. Another author (N.B.) acknowledges support from NSF Grant No. PHY-0555565 and DOE Grant No. DE-FG36-05GO85028. One of the authors (P.C.S.) acknowledges support from NSF Grant No. AST-0087172. The authors acknowledge support from the Institute for Theoretical Atomic, Molecular, and Optical Physics at the Harvard-Smithsonian Center for Astrophysics for a workshop which initiated this work.

PY - 2006

Y1 - 2006

N2 - We present quantum mechanical close-coupling calculations of collisions between two hydrogen molecules over a wide range of energies, extending from the ultracold limit to the superthermal region. The two most recently published potential energy surfaces for the H 2-H 2 complex, the so-called Diep-Johnson (DJ) [J. Chem. Phys. 112, 4465 (2000); 113, 3480 (2000)] and Boothroyd-Martin-Keogh-Peterson (BMKP) [J. Chem. Phys. 116, 666 (2002)] surfaces, are quantitatively evaluated and compared through the investigation of rotational transitions in H 2 +H 2 collisions within rigid rotor approximation. The BMKP surface is expected to be an improvement, approaching chemical accuracy, over all conformations of the potential energy surface compared to previous calculations of H 2-H 2 interaction. We found significant differences in rotational excitation/deexcitation cross sections computed on the two surfaces in collisions between two para-H 2 molecules. The discrepancy persists over a large range of energies from the ultracold regime to thermal energies and occurs for several low-lying initial rotational levels. Good agreement is found with experiment B. Maté et al., [J. Chem. Phys. 122, 064313 (2005)] for the lowest rotational excitation process, but only with the use of the DJ potential. Rate coefficients computed with the BMKP potential are an order of magnitude smaller.

AB - We present quantum mechanical close-coupling calculations of collisions between two hydrogen molecules over a wide range of energies, extending from the ultracold limit to the superthermal region. The two most recently published potential energy surfaces for the H 2-H 2 complex, the so-called Diep-Johnson (DJ) [J. Chem. Phys. 112, 4465 (2000); 113, 3480 (2000)] and Boothroyd-Martin-Keogh-Peterson (BMKP) [J. Chem. Phys. 116, 666 (2002)] surfaces, are quantitatively evaluated and compared through the investigation of rotational transitions in H 2 +H 2 collisions within rigid rotor approximation. The BMKP surface is expected to be an improvement, approaching chemical accuracy, over all conformations of the potential energy surface compared to previous calculations of H 2-H 2 interaction. We found significant differences in rotational excitation/deexcitation cross sections computed on the two surfaces in collisions between two para-H 2 molecules. The discrepancy persists over a large range of energies from the ultracold regime to thermal energies and occurs for several low-lying initial rotational levels. Good agreement is found with experiment B. Maté et al., [J. Chem. Phys. 122, 064313 (2005)] for the lowest rotational excitation process, but only with the use of the DJ potential. Rate coefficients computed with the BMKP potential are an order of magnitude smaller.

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