simulation of water carbon nanotube system including chloroform lin chen advisor: david smith...
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Simulation of water carbon nanotube system including chloroform
Lin Chen
Advisor: David Smith
October 4, 2006
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H2O
H2O and CHCl3
Two System
Chloroform water CNT system
Water CNT system
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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
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Target
Adsorption of pollutants toxins biothreat agents
Novel water purification materials development
Why the CNT show more powerfull adsorption than activated carbon?
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initial the system
+
Length: 31.748 AngstromDiameter: 8.1 Angstrom
Type: Armchair 6,6
31.748 Angstrom
H2O
T 298.15K
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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
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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
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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
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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
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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.
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Fluctuation of water number
the system arrive equilibrium
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energy calculation
boundary condition
image
Energy = L-J + Coulomb
Coulomb take long distance coulomb (ewald)
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Water CNT system
Radial distribution
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Chloroform water CNT system
Number of CHCl3 50
Radial distribution
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w(r)=-KbTln(g(r)) which represent ‘free energy’
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Number of CHCl3 20
CH Radial Distribution O Radial Distribution
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Further Research
Reduce the number of CHCl3 in the system
Conjunction of CNT
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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.