Potential energy surfaces for the photochemical reactions Ca*+H2→CaH+H

Abstract

A hierarchical family of global analytic Born-Oppenheimer potential energy surfaces for the H + H 2 reaction ranging in quality from double-zeta to the complete basis set limit Six 1 AЈ potential energy surfaces of the CaϩH 2 system have been calculated using an effective-core potential and a core-polarization potential for Ca. Large configuration interactions were performed to ensure accurate energies and wave functions. The 2 1 AЈ surface, made from Ca(4s3d, 1 D), has a very stable intermediate, and crosses with the ground state ͑1 1 AЈ͒ potential energy surface in C 2v geometry. A diabatic coupling between these two can result in the CaH product. Three potential surfaces originating from Ca(4s3d, 1 D) and two potential surfaces originating from Ca(4s4 p, 1 P) are well separated at low energy region, suggesting that the reaction product CaH from the Ca(4s4 p, 1 P) state via nonadiabatic transition to the Ca(4s3d, 1 D) surface is very unlikely. Other possible routes of producing CaH from the Ca(4s4 p, 1 P) state also appear quite improbable in the single collision process. The wave function analysis does not show any sign of electron transfer from the metal atom to the hydrogen molecule in the reactant stage, which implies that the harpooning model does not apply to this reaction.

A Neural Network Potential Energy Surface and Quantum Dynamics Study of Ca(1S) + H2(v0 = 0, j0 = 0) → CaH + H Reaction

“…15 Furthermore, the study on the Ca( 1 D) + H 2 reaction revealed that the reaction has a preference for a near C 2v collision configuration, 16 and the allocated proportions of product available energy for rotation, vibration, and translation are 0.36 ± 0.05, 0.28 ± 0.04, and 0.36 ± 0.05, respectively. 17 Theoretically, Lee et al 18 calculated six 1 A′ potential energy surfaces (PESs) of the Ca + H 2 reaction system by using an effective-core potential and a core-polarization potential for Ca. They also conducted a simple analysis of the possible reaction paths through the wave functions.…”