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Hartmut-Loewen.pdf

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3.3) Brownian dynamics of rod-like particles<br />

start from Smoluchowski picture ωˆ<br />

full probability density distribution<br />

Smoluchowski equation:<br />

(Textbook J.K.G. Dhont)<br />

∂<br />

∂t<br />

P = L Lˆ<br />

ûu ≡ ω<br />

v v<br />

r ,..., ; ˆ ,..., ˆ<br />

1 rN<br />

ω ω , t)<br />

123<br />

142<br />

243<br />

P( 1 N<br />

S<br />

P<br />

2<br />

v N<br />

N<br />

r ˆ ω<br />

total potential energy<br />

Smoluchowski operator ∑<br />

= ⎩ ⎨⎧<br />

N v t ⎡ v 1 v N N ⎤<br />

Lˆ v<br />

= ∇ v<br />

s<br />

r • D(<br />

ˆ ωi<br />

) • ⎢∇<br />

v<br />

r + ∇ v<br />

rU<br />

( r , ˆ ω , t)<br />

i<br />

i<br />

i<br />

⎥<br />

i 1<br />

⎣ kBT<br />

⎦<br />

r<br />

ˆ ˆ ∇<br />

Ri = ωi × ˆ ω<br />

⎡<br />

⎤<br />

+ ˆ • ˆ 1<br />

⎢ + ˆ v N N<br />

D<br />

( , ˆ<br />

rRi<br />

Ri<br />

RiU<br />

r ω , t)<br />

⎥<br />

⎣ kBT<br />

⎦<br />

i<br />

D( ˆ ω ) ˆ ˆ ( 1 ˆ ˆ<br />

i = D ωi<br />

⊗ ωi<br />

+ D − ωi<br />

⊗ ωi<br />

)<br />

t<br />

ll<br />

⊥ t

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