The interaction of methylene with molecular hydrogen: potential energy surface and inelastic collisions

ABSTRACT

The potential energy surface describing the interaction of methylene (CH${}_2$) in its ground ${\tilde{X}}^3{B}_1$ electronic state with molecular hydrogen has been calculated through explicitly correlated coupled cluster theory with inclusion of single, double, and (perturbatively) triple excitations [RCCSD(T)-F12a] and a correlation-consistent aug-cc-pVTZ basis. The calculated points for various geometries of the CH${}_2$–H${}_2$ complex were fit to a functional form suitable for use in time-independent quantum scattering calculations of cross sections for collision-induced transitions between CH${}_2$ rotational levels. The well depth $D_e$ of the CH${}_2$–H${}_2$ complex was found to equal 92.1 cm${}^{-1}$ in a planar geometry and intermolecular separation $R=6.55a_0$. A representative set of cross sections is presented and compared with cross sections for the corresponding transitions in methylene induced by collisions with helium.

GRAPHICAL ABSTRACT

Keywords:

• Potential energy surface
• molecule-molecule collisions
• rotational energy transfer

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The quantum chemistry calculations were performed on the Maryland Advanced Research Computing Cluster, which was funded by the state of Maryland and is jointly managed by Johns Hopkins University and the University of Maryland College Park.