An accurate many-body expansion potential energy surface for AlH2 (22A′) and quantum dynamics in Al(3P) + H2 (v0=0-3, j0=0, 2, 4, 6) collisions

An accurate potential energy surface is constructed for the excited state of AlH2 by fitting extensive ab initio points calculated at the multi-reference configuration interaction level based on aug-cc-pV(Q+d)Z and aug-cc-pV(5+d)Z basis sets. All the calculated energies are corrected via the many-body expansion method and extrapolated to the complete basis set limit. The various topographic features of the new potential energy surface are investigated to demonstrate the correct behavior of Al(P-3) + H-2(X-1 sigma(+)(g)) and AlH(a(3)pi) + H(S-2) dissociation limits. By employing the time-dependent wave packet approach, the integral scattering cross-sections obtained from the Coriolis coupling calculation and the centrifugal sudden approximation, respectively, are compared in detail and show that the former has a higher effect on the reaction. Moreover, the thermal rate constants for Al(P-3) + H-2 (v(0) = 0-3, j(0) = 0, 2, 4, 6) in the temperature range of 0-5000 K are calculated, thereby providing insights into the influence of ro-vibrational quantum numbers on the thermal rate constants.

Automated summary

An accurate potential energy surface for the excited state of AlH2 is constructed by fitting extensive ab initio points. The topographic features of the surface are investigated to demonstrate the correct behavior of the dissociation limits. The thermal rate constants for Al(P-3) + H-2 are calculated, providing insights into the influence of ro-vibrational quantum numbers.