Quantum Dynamics Studies of the Vibrational States of HO3(X2A”) Hua-Gen Yu Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973-5000 Bastiaan J. Braams Department of Mathematics and Computer Science, Emory University, Atlanta, Georgia 30322 This work was supported by the U.S. DOE under contract No. DEAC02-98CH10886. 62nd OSU International Symposium on Molecular Spectroscopy, June 20, 2007
Milestones: 1973, Blint & Newton, HF/4-31G: Introduction Milestones: 1973, Blint & Newton, HF/4-31G: HO3 is meta-stable w.r.t. OH + O2. 1986, Schaefer III et. al., MC/DZP: gauche-HO3 is stable with De=13.8 kcal/mol. 1996, Speranza, Fourier-transform ion cyclotron resonance (FTICR): HO3 is stable with D0=105 kcal/mol. 1996, Seinfeld, G2M(RCC): The stable conformer is cis-HO3 with De=9.35 kcal/mol. 1999, Cacace et.al., Neutralization/dissociation mass spectrum: The HO3 radical has a H-O-O-O connectivity with 10-6 sec. 2000, Setokuchi et.al., MRMP2/CAS(19,13): trans-HO3 is more stable than cis-HO3, and De=3.9 kcal/mol. 2005, Endo et.al., Fourier-transform microwave (FTMW): The stable trans-HO3 has a long HO-O2 bond of 1.68 Å. 2007, Lester et.al., Gas-phase infrared action spectrum: trans-HO3 has a D0 6.12 kcal/mol, and its IR lines are broadened.
Why is the central O-O bond in trans-HO3 so long ? Introduction Q/A: Stability: D0 6.12 kcal/mol Structure: trans-HO3 Why is the central O-O bond in trans-HO3 so long ? electronic and/or dynamical What is the reason behind the broadening of spectral lines ? Where is the cis-HO3 conformer ?
Energy diagram calculated with HCTH/aVTZ for HO3(X2A”)
Diatom-diatom Jacobi Coordinates and normal modes
Minimum energy path for the HO3 OH + O2 reaction and calculated binding energy of HO3 Lester et. al., JPC A 111, 4727 (2007). D0(expt) 2140 cm-1
Vibrational (6D) energy levels in the torsion mode of HO3 198.7
Vibrational (1D) wavefunctions in the torsion mode of HO3 The level splitting is not just due to the torsional motion.
2D potential energy surface with fixed Rs and optimized 2 Eb <> 800 cm-1 t-HO3 c-HO3 Energy level splittings result from the m-D dynamical tunneling effect.
Rovibrational energy levels in cm-1 for the ground-state HO3 A = 75.8387 GHz (B-C)/2 = 0.6395 GHz (B+C)/2 = 9.7688 GHz 0.4cm-1 E0‘(K=1) 0.4cm-1 v6 (K=1) 1.4cm-1 2v6 (K=1) 2.0cm-1 3v6 (K=1) 0.01cm-1 c-HO3: 99.7063, 11.1044, 10.2320 GHz
Why is the central O-O bond in trans-HO3 so long ? Summary Q/A: Stability: D0 6.12 kcal/mol Structure: trans-HO3 Why is the central O-O bond in trans-HO3 so long ? electronic and/or dynamical What is the reason behind the broadening of spectral lines ? multi-dimensional dynamic tunneling Where is the cis-HO3 conformer ? 388 cm-1 w.r.t. trans-HO3 with a lifetime of about 4 ns
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The O-O exchange symmetry with Eb = 1.301 eV