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Chemical Dynamics in Aqueous Media

Chemical Dynamics in Aqueous Media. Amalendu Chandra Department of Chemistry, Indian Institute of Technology Kanpur, India 208016. ATIP 1 st Workshop on HPC in India @ SC-09. Hydrogen bonded (tetrahedral) structure of water. Hydrogen bond fluctuations in water and aqueous solutions.

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Chemical Dynamics in Aqueous Media

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  1. Chemical Dynamics in Aqueous Media Amalendu Chandra Department of Chemistry, Indian Institute of Technology Kanpur, India 208016 Workshop on HPC in India ATIP 1st Workshop on HPC in India @ SC-09

  2. Hydrogen bonded (tetrahedral) structure of water ATIP 1st Workshop on HPC in India @ SC-09

  3. Hydrogen bond fluctuations in water and aqueous solutions ATIP 1st Workshop on HPC in India @ SC-09

  4. Excess proton in water ATIP 1st Workshop on HPC in India @ SC-09

  5. Experimental Methods • X-ray and Neutron Scattering • Low frequency Raman ( < 200 cm-1) • Time Resolved Infrared Spectroscopy Transient hole burning studies using IR laser ATIP 1st Workshop on HPC in India @ SC-09

  6. Pump-probe signal at different delay times Variation of H-bond distance with time Relaxation time ~ 1.0 ps G.M.Gale etal PRL, 82, 1068 (1999) = ~ 100-200 fs, ~ 1-2 ps A. Tokmakoff and coworkers JCP (2005) M.D. Fayer and coworkers, PNAS (2007) ATIP 1st Workshop on HPC in India @ SC-09

  7. Computation of Aqueous Systems ATIP 1st Workshop on HPC in India @ SC-09

  8. Ab initioMolecular Dynamics Forces are calculated from electronic structure calculation that are performed on-the-fly as the MD trajectory is generated. Car-Parrinello Method: R. Car and M. Parrinello, Phys. Rev. Lett., 55, 2471 (1985) J. Hutter et al. CPMD, MPI Stuttgart and IBM Zurich ATIP 1st Workshop on HPC in India @ SC-09

  9. OH stretch frequency vs time in liquid water • Chandra and coworkers, • JPC/A (2008); JCP (2008) ATIP 1st Workshop on HPC in India @ SC-09

  10. Frequency vs hydrogen bond distance (pure D2O) ATIP 1st Workshop on HPC in India @ SC-09

  11. Dynamics of vibrational spectral diffusion: Hole creation and subsequent dynamics from nonequilibrium probability distributions Hole creation: Monte Carlo algorithm ATIP 1st Workshop on HPC in India @ SC-09

  12. Dynamics after hole creation: Excitation in blue/red Experiments: G.M. Gale et al PRL (1999) ATIP 1st Workshop on HPC in India @ SC-09

  13. Time dependence of average frequency after hole creation 1 ~ 100 fs (dynamics of intact hydrogen bonds) 2 ~ 2 ps (lifetimes of hydrogen bonds) s ~ 100 cm-1 (intermolecular stretching/bending vibrations) A. Chandra and coworkers, JPC/A (2008); JCP (2009) ATIP 1st Workshop on HPC in India @ SC-09

  14. ScH2O 673K/0.0221 573K/0.0338 423K/0.0334 298K/0.0334 Supercritical water A.K Soper et al., JCP, 106, 249 (1996) ATIP 1st Workshop on HPC in India @ SC-09

  15. Correlations between OD frequency and D..O distance A. Chandra and coworkers, JPC/A (2008) ATIP 1st Workshop on HPC in India @ SC-09

  16. Proton Transfer in water Eigen Zundel complex ATIP 1st Workshop on HPC in India @ SC-09

  17. Proton Migration Dynamics DH3O+= 9.31x10-5 cm2/s Mobility of H3O+ in liquid water DH2O = 2.30x10-5 cm2/s Mobility of OH- in liquid water D OH_= 5.3x10-5 cm2/s M.E. Tuckerman, D.Marx and M. Parrinello, Nature, 417, 925 (2002) A.Chandra, M. Tuckerman and D.Marx, PRL (2007); Acc. Chem. Res. (2006) ATIP 1st Workshop on HPC in India @ SC-09 M.E. Tuckerman, D.Marx and M. Parrinello, Nature, 417, 925 (2002)

  18. Protonic defects in water clusters Where is the protonic defect located? Is there any proton transfer in clusters? A. Bankura and A. Chandra, JCP (submitted) ATIP 1st Workshop on HPC in India @ SC-09

  19. Long Range (LR) Short Range (SR) QM Density Quantum-classical simulations QM/MM Technique Describes chemically relevant part of large system using quantum mechanics (QM) and rest by molecular mechanics (MM) H3O+/OH- in different carbon nanotube systems Effects of confinement

  20. Group members: Financial support: DST, CSIR, BRNS, MCIT (Government of India) AvH Foundation (Germany) ATIP 1st Workshop on HPC in India @ SC-09

  21. IIT Kanpur …. ATIP 1st Workshop on HPC in India @ SC-09

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