A full-dimensional quantum dynamical study of H2+H2 collisions: Coupled-states versus close-coupling formulation

Alex Bohr, Stephen Paolini, Robert C. Forrey, N. Balakrishnan, P. C. Stancil

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11 Scopus citations


Collision-induced energy transfer involving H2 molecules plays an important role in many areas of physics. Kinetic models often require a complete set of state-to-state rate coefficients for H2+H2 collisions in order to interpret results from spectroscopic observations or to make quantitative predictions. Recent progress in full-dimensional quantum dynamics using the numerically exact close-coupling (CC) formulation has provided good agreement with existing experimental data for low-lying states of H2 and increased the number of state-to-state cross sections that may be reliably determined over a broad range of energies. Nevertheless, there exist many possible initial states (e.g., states with high rotational excitation) that still remain elusive from a computational standpoint even at relatively low collision energies. In these cases, the coupled-states (CS) approximation offers an alternative full-dimensional formulation. We assess the accuracy of the CS approximation for H2+H2 collisions by comparison with benchmark results obtained using the CC formulation. The results are used to provide insight into the orientation effects of the various internal energy transfer mechanisms. A statistical CS approximation is also investigated and cross sections are reported for transitions which would otherwise be impractical to compute.

Original languageEnglish (US)
Article number064308
JournalJournal of Chemical Physics
Issue number6
StatePublished - Feb 14 2014

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry


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