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Simulation of water carbon nanotube system including chloroform

Simulation of water carbon nanotube system including chloroform. Lin Chen Advisor: David Smith. October 4, 2006. Water CNT system. H 2 O. Two System. Chloroform water CNT system. H 2 O and CHCl 3. Overview of Talk. Why we study this topic System set up initial the system

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Simulation of water carbon nanotube system including chloroform

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  1. Simulation of water carbon nanotube system including chloroform Lin Chen Advisor: David Smith October 4, 2006

  2. Water CNT system H2O Two System Chloroform water CNT system H2O and CHCl3

  3. Overview of Talk • Why we study this topic • System set up • initial the system • movement trial • insert and delete trial • energy calculation • Water CNT system • Chloroform CNT system • Further research

  4. Target Adsorption of pollutants toxins biothreat agents Novel water purification materials development Why the CNT show more powerfull adsorption than activated carbon?

  5. initial the system Type: Armchair 6,6 Length: 31.748 Angstrom Diameter: 8.1 Angstrom 31.748 Angstrom + T 298.15K H2O

  6. Lennard-Jones Potential Water σ 3.166 Angstrom ε 0.650 KJ mol-1 qH +0.4238 qO -0.8476 rOH 1 Angstrom rHH 1.63 Angstrom

  7. Chloroform ‘united atom’ CH σCH 3.8 Angstrom εCH 0.3344 KJ mol-1 σCl 3.47Angstrom εCl 1.672 KJ mol-1 r_CH_Cl 1.758 Angstrom angle_Cl_CH_Cl 111.3 qCH +0.42 qCl -0.14 Carbon σC 3.4 Angstrom εC 0.2325 KJ mol-1

  8. movement trial move the particle from old position to new position and orientation Accept factor acc(o->n) = exp[-(U(n)-U(o))/kbT] Monte Carlo method accept U(n) < U(o) rand < acc(o->n)

  9. Optimization of Movemenmt Parameters Translational move • single-particle trial move mscale1=0.07 Orientational move • quaternion mscale=0.7 Final choice mscale mscale1 mscale(CHCl3) mscale1(CHCl3) pure water 0.7 0.03 CHCl3 solution 0.5 0.05 1.1 0.07

  10. insert and delete trial insert • Insert 'trial particle' at random place/orientation • Calculate us (single particle energy) • accept or reject based on accept factor Acceptfactor = R * (exp(us-uo)/kbT u0 chose to represent pure H2O at room temperature and normal pressure. delete • Randomly select 'trial particle' • Calculate us (single particle energy) • accept or reject the trial based on accept factor Acceptfactor = R’ * (exp(uo-us)/kbT

  11. Fluctuation of water number the system arrive equilibrium

  12. energy calculation boundary condition image Energy = L-J + Coulomb Coulomb take long distance coulomb (ewald)

  13. Water CNT system Radial distribution

  14. Chloroform water CNT system Number of CHCl3 50 Radial distribution

  15. w(r)=-KbTln(g(r)) which represent ‘free energy’

  16. Number of CHCl3 20 O Radial Distribution CH Radial Distribution

  17. Further Research Reduce the number of CHCl3 in the system Conjunction of CNT

  18. Reference • Frenkel, D.; Smit, B. Molecular Simulation from Algorithms to Applications: Elsevier, 1996. • Hummer, G.; Rasalah, J. C. & Noworyta, J. P. Nature. 2001, 414, 188-190. • Striolo, A.; Chialvo, A. A.; Gubbins, K. E. & Cummings, P. T. J. Chem. Phys.2005,122, 234712. • Mezei, M. Molecular Simulation, 1992, 9, 257-261. • Mcdonald, N. A.; Carlson, H. A. & Jorgensen, W. L. J. Phys. Org. Chem. 1997, 10, 563-567.

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