1. Quantum Dynamics Studies of the Vibrational States of HO3(X2A”)
Hua-Gen Yu
Department of Chemistry, Brookhaven National Laboratory, Upton, NY
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

2. 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=105 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  kcal/mol, and its IR lines are broadened.

3. Why is the central O-O bond in trans-HO3 so long ?
Introduction
Q/A:
Stability: D0  kcal/mol 
Structure: trans-HO 
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 ?

4. Energy diagram calculated with HCTH/aVTZ for HO3(X2A”)

5. Diatom-diatom Jacobi Coordinates and normal modes

6. 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

7. Vibrational (6D) energy levels in the torsion mode of HO3
198.7

8. Vibrational (1D) wavefunctions in the torsion mode of HO3
The level splitting is not just due to the torsional motion.

9. 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.

10. Rovibrational energy levels in cm-1 for the ground-state HO3
A = GHz
(B-C)/2 = GHz
(B+C)/2 = 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: , , GHz

11. Why is the central O-O bond in trans-HO3 so long ?
Summary
Q/A:
Stability: D0  kcal/mol 
Structure: trans-HO 
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

12. Thanks

13. The O-O exchange symmetry with Eb = 1.301 eV