Accurate electronic structure calculations of ground and electronically-excited potential energy surfaces for atmospherically important molecules

Current and Recent Projects:

• Potential energy surfaces for reactions of mercury with reactive halogens, e.g., Hg + {Br₂, BrCl, BrO}
• Chemically-accurate thermochemistry for Hg- and Cd-containing species
• Electronic spectra of hydrogen peroxide-water complexes (with J. Francisco, Purdue Univ.)
• Potential energy surfaces for the O(¹D, ³P) + HCl reactions including spin-orbit couplings
• Potential energy surfaces of HOBr for unimolecular decomposition and the photodissociation process HOBr + hv → OH + Br
• Spin-orbit effects in atoms and small molecules: {F, Cl, Br}, BrCl, BrO, and HOBr
• Accurate prediction of rotational-vibration spectra of OClO, OBrO, HOCl, and HOBr from accurate 3-D ab initio potential energy functions.
• Large-scale potential energy surfaces of HOCl for describing vibrational energy transfer leading to OH + Cl

This material is based upon work supported by the National Science Foundation under Grant Nos. CHE-9501262 and CHE-0111282

The global potential energy surface for the reaction of HgBr with Br features 3 reaction channels:

Recombination: HgBr + Br → HgBr₂
Abstraction: HgBr + Br → Hg + Br₂
Exchange: HgBr + Br → BrHg + Br

At 298K, the thermal rates are calculated to be fast and nearly equal for all 3 product channels. Oxidation of Hg by Br₂ is calculated to be very slow at this temperature.

N.B. Balabanov, B.C. Shepler, and K.A. Peterson, J. Phys. Chem. A, submitted (6/05).

In the photodissociation of OClO,

two electronic states of the O₂ product is observed: the ground and first excited states. Using large configuration interaction wave functions, 2-D portions of the exit channel were calculated to produce the figure at the right. The ²B₂surface produces a¹Δ O₂, while the ²A₁surface produces X³Σ^- O₂. The lateness of the crossing suggests that more a¹Δ O₂ will be formed, which is consistent with experiment.

K.A. Peterson and H.-J. Werner, J. Chem. Phys. 105, 9823 (1996).