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Workshop on HPC in India
Chemical Dynamics in Aqueous Media
Amalendu ChandraDepartment of Chemistry, Indian
Institute of Technology Kanpur, India 208016
ATIP 1st Workshop on HPC in India @ SC-09
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 2
Hydrogen bonded (tetrahedral) structure of water
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 3
Hydrogen bond fluctuations in water and aqueous solutions
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 4
Excess proton in water
A. Chandra 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
A. Chandra 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 psG.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)
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 7
Computation of Aqueous Systems
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 8
Ab initio Molecular Dynamics
Forces are calculated from electronic structure calculation that areperformed 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
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 9
A. Chandra and coworkers, JPC/A (2008); JCP (2008)
OH stretch frequency vs time in OH stretch frequency vs time in liquid waterliquid water
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 10
Frequency vs hydrogen bond distance Frequency vs hydrogen bond distance (pure D(pure D22OO))
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 11
Dynamics of vibrational spectral diffusion:
Hole creation and subsequent dynamics from Hole creation and subsequent dynamics from nonequilibrium probability distributionsnonequilibrium probability distributions
Hole creation: Monte Carlo algorithm
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 12
Dynamics after hole creation: Excitation in Dynamics after hole creation: Excitation in blue/redblue/red
Experiments:G.M. Gale et al PRL (1999)
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 13
Time dependence of average frequency after Time dependence of average frequency after hole creationhole 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)
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 14
ScH2OSupercritical Supercritical waterwater
673K/0.0221
573K/0.0338423K/0.0334298K/0.0334
A.K Soper et al., JCP, 106, 249 (1996)A.K Soper et al., JCP, 106, 249 (1996)
A. Chandra 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)
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 16
Proton Transfer in Proton Transfer in waterwaterEigen Eigen Zundel Zundel
complexcomplex
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 17
Mobility of H3O+ in liquid
water
D H3O+
= 9.31x10-5 cm2/s
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)
Proton Migration Dynamics
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 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)
Describes chemically relevant part of large system using quantum mechanics (QM) and rest by molecular mechanics (MM)
QM/MM Technique
Long Range (LR)
Short Range (SR)
QM Density
H3O+/OH- in different carbon nanotube systems
Effects of confinement
Quantum-classical simulations
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 20
Financial support:DST, CSIR, BRNS, MCIT (Government of India)AvH Foundation (Germany)
Group members:
A. Chandra ATIP 1st Workshop on HPC in India @ SC-09 21
IIT Kanpur ….