Simulation of water carbon nanotube system including chloroform

Lin Chen

Advisor: David Smith

October 4, 2006

H2O

H2O and CHCl3

Two System

Chloroform water CNT system

Water CNT system

Overview of TalkWhy 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

Target

Adsorption of pollutants toxins biothreat agents

Novel water purification materials development

Why the CNT show more powerfull adsorption than activated carbon?

initial the system

+

Length: 31.748 AngstromDiameter: 8.1 Angstrom

Type: Armchair 6,6

31.748 Angstrom

H2O

T 298.15K

Lennard-Jones Potential

Water

σ 3.166 Angstrom

ε 0.650 KJ mol-1

qH +0.4238

qO -0.8476

rOH 1 AngstromrHH 1.63 Angstrom

Chloroform

σCH 3.8 Angstrom

εCH 0.3344 KJ mol-1

σCl 3.47Angstrom

εCl 1.672 KJ mol-1

σC 3.4 Angstrom

ε C 0.2325 KJ mol-1

Carbon

r_CH_Cl 1.758 Angstromangle_Cl_CH_Cl 111.3

qCH +0.42

qCl -0.14

‘united atom’ CH

movement trial

acc(o->n) = exp[-(U(n)-U(o))/kbT]

accept U(n) < U(o) rand < acc(o->n)

move the particle from old position to new position and orientation

Accept factor

Monte Carlo method

Optimization of Movemenmt Parameters

Translational move

single-particle trial move

Orientational move

quaternion

mscale1=0.07

mscale=0.7

mscale mscale1 mscale(CHCl3) mscale1(CHCl3) pure water 0.7 0.03 CHCl3 solution 0.5 0.05 1.1 0.07

Final choice

insert and delete trial

insert

delete

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

Randomly select 'trial particle'

Calculate us (single particle energy)

accept or reject the trial based on accept factor

Acceptfactor = R’ * (exp(uo-us)/kbT

u0 chose to represent pure H2O at room temperature and normal pressure.

Fluctuation of water number

the system arrive equilibrium

energy calculation

boundary condition

image

Energy = L-J + Coulomb

Coulomb take long distance coulomb (ewald)

Water CNT system

Radial distribution

Chloroform water CNT system

Number of CHCl3 50

Radial distribution

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

Number of CHCl3 20

CH Radial Distribution O Radial Distribution

Further Research

Reduce the number of CHCl3 in the system

Conjunction of CNT

Reference

Frenkel, D.; Smit, B. Molecular Simulation from Algorithms to

Applications: Elsevier, 1996.

Hummer, G.; Rasalah, J. C. & Noworyta, J. P. Nature. 2001, 414, 18

8-190.

Striolo, A.; Chialvo, A. A.; Gubbins, K. E. & Cummings, P. T. J. Che

m. Phys. 2005,122, 234712.

Mezei, M. Molecular Simulation, 1992, 9, 257-261.

Mcdonald, N. A.; Carlson, H. A. & Jorgensen, W. L. J. Phys. Org. Ch

em. 1997, 10, 563-567.