1. Structural Evolution & Solvation of OH radical in (H 2 O) n +, n=5~8 En-Ping Lu, Piin-Ruey Pan, Ying-Cheng Li and Jer-Lai Kuo Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan Ming-Kang Tsai Dept of Chem., National Taiwan Normal University, Taipei, Taiwan 69 th OSU Int. Symp. on Mol. Spectroscopy, University of Illinois Urbana-Champaign, USA, June/19/2014

2. (H 2 O) 2 + : Proton Transferred (PT) or Hemi-Bonded (HB) Pan et al. PCCP, 14, 10705 (2012) PTHBTS  E (kcal/mol) PTTSHB BLYP0.00 -7.27 B3LYP0.007.510.27 BH&HLYP0.0016.4110.86 MP20.0018.7913.92 CCSD(T)0.0015.148.80

3. (H 2 O) n + vs. H + (H 2 O) n Mizuse, Kuo, Fujii, Chem. Sci., 2, 868 (2011)

4. (H 2 O) n +, n=3~8 w/o Ar Mizuse, Kuo, Fujii, Chem. Sci., 2, 868 (2011) Mizuse & Fujii, J. Phys. Chem. A., 117, 929 (2013) Spectra w/o Ar differ for n=7 (temp?) Many isomers contribute to spectra

5. How to generate Structures (1)? Basin-Hopping MC algorithm + B3LYP/6-31+G* Do & Besley J. Phys. Chem. A., 117, 5385 (2013) Refined MP2/6-311++G**

6. How to generate Structures (2)? The similarity of H-Bond network Ionization process e-e- (H 2 O) n : Nguyen, Ong, Kuo, J. Chem. Theory Comp., 5, 2629 (2009). H + (H 2 O) n : Nguyen, Ong, Soh, Kuo, J. Phys. Chem. A, 112, 6257 (2008) Re-optimized by BH&HLYP/aug-cc-pvDZ& B3LYP/6-31+G* (for comparison) Our 1 st -Principle Search Method

7. Diff. Structures of (H 2 O) n +, n=5~8 We found more stable isomers than Besely for n=7 & 8.

8. Energy of (H 2 O) n +, n=5~8 Many isomers with similar energy, proper sampling is needed.

9. Taking Statistical Averages Harmonic Superposition Approximation(HSA) Contribution from ALL isomers can be computed by HSA. For relevant temp. only a sub-set is needed.

10. Topology of (H 2 O) n + at diff. Temp. Structure/Topology of clusters are sensitive to temperature.

11. Coordination # of OH radical Coord. # of OH radical is more than 1 for n=6, 7 & 8.

12. IR Spectra of (H 2 O) 7 + w/o Ar Two new vib. bands assigned + Temp-dep. features captured.

13. IR Spectra of (H 2 O) n +, n=5~8 Vib. band ~ 3200 cm -1 is assigned to fully solvated OH. Direct evidence of solvated OH radical for n ≥ 7.

14. For n ≤ 5, OH prefer to stay at terminal site. Fully solvated OH appears at n ≥ 6, dominates for n ≥ 7. PT is Hm more stable (~ 10 kcal/mol). Be careful with the E xc used. Vib. band ~ 3200 cm -1 is assigned to fully solvated OH. Conclusion Energy Landscape of (H 2 O) n + is rough, Proper sampling of structures is required/important. $$ =