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

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Presentation on theme: "Simulation of water carbon nanotube system including chloroform Lin Chen Advisor: David Smith October 4, 2006."— Presentation transcript:

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

2 H2OH2O H 2 O and CHCl 3 Two System Chloroform water CNT system Water CNT system

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 + Length: 31.748 Angstrom Diameter: 8.1 Angstrom Type: Armchair 6,6 31.748 Angstrom H2O T 298.15K

6 Lennard-Jones Potential Water σ 3.166 Angstrom ε 0.650 KJ mol-1 q H +0.4238 q O -0.8476 r OH 1 Angstrom r HH 1.63 Angstrom

7 Chloroform σ CH 3.8 Angstrom ε CH 0.3344 KJ mol-1 σ Cl 3.47Angstrom ε Cl 1.672 KJ mol-1 σ C 3.4 Angstrom ε C 0.2325 KJ mol-1 Carbon r_CH_Cl 1.758 Angstrom angle_Cl_CH_Cl 111.3 q CH +0.42 q Cl -0.14 ‘united atom’ CH

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

9 Optimization of Movemenmt Parameters Translational move  single-particle trial move Orientational move  quaternion mscale1=0.07 mscale=0.7 mscale mscale1 mscale(CHCl 3 ) mscale1(CHCl 3 ) pure water 0.7 0.03 CHCl 3 solution 0.5 0.05 1.1 0.07 Final choice

10 insert and delete trial insert delete  Insert 'trial particle' at random place/orientation  Calculate u s (single particle energy)  accept or reject based on accept factor Acceptfactor = R * (exp(u s -u o )/k b T  Randomly select 'trial particle'  Calculate u s (single particle energy)  accept or reject the trial based on accept factor Acceptfactor = R ’ * (exp(u o -u s )/k b T u 0 chose to represent pure H 2 O at room temperature and normal pressure.

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 CHCl 3 50 Radial distribution

15 w(r)=-K b Tln(g(r)) which represent ‘free energy’

16 Number of CHCl 3 20 CH Radial Distribution O Radial Distribution

17 Further Research Reduce the number of CHCl 3 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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