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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@1090 f3b2605a-c512-4ea7-a41b-209d697bcdaa

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sjplimp 2007-10-22 22:21:53 +00:00
parent df57eab562
commit acf51990bf
2 changed files with 22 additions and 18 deletions
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20
doc/pair_colloid.html
View File

@ -36,7 +36,7 @@ Lennard-Jones particle of size sigma.
</P>
<CENTER><IMG SRC = "Eqs/pair_colloid_cc.jpg">
</CENTER>
<P>A is the Hamaker constant, a1 and a2 are the radii of the two
<P>A_cc is the Hamaker constant, a1 and a2 are the radii of the two
colloidal particles, and Rc is the cutoff. This equation results from
describing each colloidal particle as an integrated collection of
Lennard-Jones particles of size sigma and is derived in
@ -46,8 +46,8 @@ Lennard-Jones particles of size sigma and is derived in
</P>
<CENTER><IMG SRC = "Eqs/pair_colloid_cs.jpg">
</CENTER>
<P>A is the Hamaker constant, a is the radius of the colloidal particle,
and Rc is the cutoff. This formula is derived from the
<P>A_cs is the Hamaker constant, a is the radius of the colloidal
particle, and Rc is the cutoff. This formula is derived from the
colloid-colloid interaction, letting one of the particle sizes go to
zero.
</P>
@ -56,7 +56,8 @@ Lennard-Jones formula
</P>
<CENTER><IMG SRC = "Eqs/pair_colloid_ss.jpg">
</CENTER>
<P>which results from letting both particle sizes go to zero.
<P>with A_ss set appropriately, which results from letting both particle
sizes go to zero.
</P>
<P>The following coefficients must be defined for each pair of atoms
types via the <A HREF = "pair_coeff.html">pair_coeff</A> command as in the examples
@ -70,19 +71,20 @@ commands, or by mixing as described below:
<LI>d2 (distance units)
<LI>cutoff (distance units)
</UL>
<P>A is the energy prefactor and should typically be set as follows:
<P>A is the Hamaker energy prefactor and should typically be set as
follows:
</P>
<UL><LI>A_cc = colloid/colloid = 4 pi^2 = 39.5
<LI>A_ss = solvent/solvent = 144 (assuming epsilon = 1, so that 144/36 = 4)
<LI>A_cs = colloid/solvent = sqrt(A_cc*A_ss)
<LI>A_cs = colloid/solvent = sqrt(A_cc*A_ss)
<LI>A_ss = solvent/solvent = 144 (assuming epsilon = 1, so that 144/36 = 4)
</UL>
<P>Sigma is the size of the solvent particle or the constituent particles
integrated over in the colloidal particle and should typically be set
as follows:
</P>
<UL><LI>Sigma_cc = colloid/colloid = 1.0
<LI>Sigma_ss = solvent/solvent = 1.0 or whatever size the solvent particle is
<LI>Sigma_cs = colloid/solvent = arithmetic mixing between colloid sigma and solvent sigma
<LI>Sigma_cs = colloid/solvent = arithmetic mixing between colloid sigma and solvent sigma
<LI>Sigma_ss = solvent/solvent = 1.0 or whatever size the solvent particle is
</UL>
<P>Thus typically Sigma_cs = 1.0, unless the solvent particle's size !=
1.0.

20
doc/pair_colloid.txt
View File

@ -33,7 +33,7 @@ The colloid-colloid interaction energy is given by
:c,image(Eqs/pair_colloid_cc.jpg)
A is the Hamaker constant, a1 and a2 are the radii of the two
A_cc is the Hamaker constant, a1 and a2 are the radii of the two
colloidal particles, and Rc is the cutoff. This equation results from
describing each colloidal particle as an integrated collection of
Lennard-Jones particles of size sigma and is derived in
@ -43,8 +43,8 @@ The colloid-solvent interaction energy is given by
:c,image(Eqs/pair_colloid_cs.jpg)
A is the Hamaker constant, a is the radius of the colloidal particle,
and Rc is the cutoff. This formula is derived from the
A_cs is the Hamaker constant, a is the radius of the colloidal
particle, and Rc is the cutoff. This formula is derived from the
colloid-colloid interaction, letting one of the particle sizes go to
zero.
@ -53,7 +53,8 @@ Lennard-Jones formula
:c,image(Eqs/pair_colloid_ss.jpg)
which results from letting both particle sizes go to zero.
with A_ss set appropriately, which results from letting both particle
sizes go to zero.
The following coefficients must be defined for each pair of atoms
types via the "pair_coeff"_pair_coeff.html command as in the examples
@ -67,19 +68,20 @@ d1 (distance units)
d2 (distance units)
cutoff (distance units) :ul
A is the energy prefactor and should typically be set as follows:
A is the Hamaker energy prefactor and should typically be set as
follows:
A_cc = colloid/colloid = 4 pi^2 = 39.5
A_ss = solvent/solvent = 144 (assuming epsilon = 1, so that 144/36 = 4)
A_cs = colloid/solvent = sqrt(A_cc*A_ss) :ul
A_cs = colloid/solvent = sqrt(A_cc*A_ss)
A_ss = solvent/solvent = 144 (assuming epsilon = 1, so that 144/36 = 4) :ul
Sigma is the size of the solvent particle or the constituent particles
integrated over in the colloidal particle and should typically be set
as follows:
Sigma_cc = colloid/colloid = 1.0
Sigma_ss = solvent/solvent = 1.0 or whatever size the solvent particle is
Sigma_cs = colloid/solvent = arithmetic mixing between colloid sigma and solvent sigma :ul
Sigma_cs = colloid/solvent = arithmetic mixing between colloid sigma and solvent sigma
Sigma_ss = solvent/solvent = 1.0 or whatever size the solvent particle is :ul
Thus typically Sigma_cs = 1.0, unless the solvent particle's size !=
1.0.