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.