Potential energy surface of the A state of NH{sub 2}, and the role of excited states in the N({sup 2}D) + H{sub 2} reaction.

Journal Article · Thu Mar 23 04:00:00 EST 2000 · J. Phys. Chem. A

DOI:https://doi.org/10.1021/jp9924575· OSTI ID:942660

Pederson, L A; Schatz, G C; Hollebeek, T; Ho, T -S; Rabitz, H; Harding, L B

We present a global potential energy surface for the {tilde A} state of NH{sub 2} (1{sup 2}A') based on application of the reproducing kernel Hilbert space (RKHS) interpolation method to high-quality ab initio (multireference configuration-interaction) results. This surface correlates adiabatically to the a{sup 1-}{Delta} state of NH, with a reaction endoergicity of about 8 kcal/mol, but it can also lead to formation of ground-state NH (exoergic by 29 kcal/mol) via nonadiabatic (Renner-Teller) interactions for linear HNH geometries that lie near the bottom of a 94 kcal/mol deep well that is accessible from N({sup 2}D) + H{sub 2} by insertion over a 3.4 kcal/mol barrier. This insertion barrier is about 1 kcal/mol higher in energy than the corresponding insertion barrier associated with the ground state of NH{sub 2}(1{sup 2-}A'). As a result, the {tilde A} state contributes measurably to both the thermal rate constant for N({sup 2}D) + H{sub 2} and the rate for NH(a{sup 1}{Delta}) production. Extensive quasiclassical trajectory calculations are performed on the RKHS surface to study the N({sup 2}D) + H{sub 2} reaction dynamics, with the nonadiabatic rate constant estimated using a capture model. We find that the cross section for ground-state NH production is comparable to that obtained on the ground-state 1A' surface, except for a 1 kcal/mol shift upward in the effective threshold due to the different barrier height. The cross section for NH(a{sup 1}{Delta}) production has a higher threshold energy and is about 15% of the ground-state cross section at energies well above threshold.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 942660
• Report Number(s): ANL/CHM/JA-33578
• Journal Information: J. Phys. Chem. A, Journal Name: J. Phys. Chem. A Journal Issue: 11 ; Mar. 23, 2000 Vol. 104; ISSN 1089-5639; ISSN JPCAFH
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CONFIGURATION INTERACTION
DEUTERIUM COMPOUNDS
EXCITED STATES
GROUND STATES
HILBERT SPACE
HYDROGEN
NITROGEN HYDRIDES
POTENTIAL ENERGY
THRESHOLD ENERGY