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On 17/01/2012 7:37 PM, dina dusti wrote:
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cite="mid:1326789466.97317.YahooMailNeo@web121304.mail.ne1.yahoo.com"
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<div id="yiv671780235yui_3_2_0_16_132678534862140">Dear
Specialists,<span><br>
</span></div>
<div id="yiv671780235yui_3_2_0_16_132678534862188"><br
id="yiv671780235yui_3_2_0_16_1326785348621779">
</div>
<div id="yiv671780235yui_3_2_0_16_132678534862189">I am a
beginner in grmacs and I have several questions about
formation of micelle in gromacs. Please help me.</div>
<div id="yiv671780235yui_3_2_0_16_132678534862198">1- We
know that there is a thermodynamic equilibrium between
created micelle and free monomers in solvent, but I
don't see this in results of my simulation! When I add
the number of monomers, all of them are aggregated
depend of concentration of solution in one micelle
(spherical to cylindrical) or several micelles and
always, lack of single monomer is the most stable state
for system. also, I didn't find this in previous work by
gromacs. Is it the limitation of gramacs? Why?<br>
</div>
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<br>
It has nothing to do with GROMACS, and likely everything to do with
your choice of model physics and the degree of convergence of the
simulation.<br>
<br>
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cite="mid:1326789466.97317.YahooMailNeo@web121304.mail.ne1.yahoo.com"
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<div id="yiv671780235yui_3_2_0_16_1326785348621332">2-
What is the relation of radius of gyration with
effective radius of spherical micelle that in many of
papers have been pointed to
R(micelle)=(1.291)R(gyration)?</div>
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<br>
I don't understand your question, or how it relates to GROMACS :)<br>
<br>
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cite="mid:1326789466.97317.YahooMailNeo@web121304.mail.ne1.yahoo.com"
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<div id="yiv671780235yui_3_2_0_16_1326785348621525">3-
Where is the center of mass of micelle in gromacs,
exactly? I obtained rdf for tails of surfactants with
center of mass of micelle that the first part of file is
as following:( I work with martini and we know that
sigma= 0.47 nm in L-J)<br>
</div>
<div id="yiv671780235yui_3_2_0_16_1326785348621606">
0 0<br>
0.002 0<br>
0.004 0<br>
0.006 0<br>
0.008 0<br>
0.01 0<br>
0.012 0<br>
0.014 0<br>
0.016 0<br>
0.018 0<br>
0.02 0<br>
0.022 0<br>
0.024 0<br>
0.026 0<br>
0.028 0<br>
0.03 0<br>
0.032 0<br>
0.034 91.8328<br>
0.036 0<br>
0.038 0<br>
0.04 0<br>
0.042 60.1866<br>
0.044 0<br>
0.046 50.176<br>
0.048 46.0824<br>
0.05 42.4701<br>
0.052 39.2663<br>
0.054 0<br>
0.056 33.8578<br>
0.058 0<br>
0.06 29.4943<br>
0.062 27.6223<br>
0.064 0<br>
0.066 48.7518<br>
0.068 0<br>
0.07 21.6699<br>
0.072 0<br>
0.074 19.3906<br>
0.076 0<br>
0.078 0<br>
0.08 82.9561<br>
0.082 47.3753<br>
0.084 0<br>
0.086 0<br>
0.088 0<br>
0.09 39.3277<br>
0.092 0<br>
0.094 12.0173<br>
0.096 23.0438<br>
0.098 11.0564<br>
0.1 0<br>
0.102 20.4125<br>
0.104 19.635<br>
0.106 9.45052<br>
0.108 9.10376<br>
0.11 17.5514<br>
0.112 0<br>
0.114 0<br>
0.116 7.89139</div>
<div id="yiv671780235yui_3_2_0_16_1326785348621729">...............................<br>
</div>
<div id="yiv671780235yui_3_2_0_16_1326785348621730">................................<br>
</div>
<div id="yiv671780235yui_3_2_0_16_1326785348621731">...............................<br>
</div>
<div id="yiv671780235yui_3_2_0_16_1326785348621732">What
does it mean? Does it say me that the center of micelle
is where the end of tails reach together. Do the tails
bond in the center of micelle together or there is a
hole according to my result and what is your definition
in gromacs for center of mass of micelle, hole or bond
between tails, Please? <br>
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<br>
We don't even know whether your micelles should have monomer tails
in the center or outside, or how you generated those numbers or what
they are. If that's a radial distribution function, then you
probably want to choose a narrower bin width for computing it, and
get a lot more samples to go in it.<br>
<br>
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<div id="yiv671780235yui_3_2_0_16_13267853486211492">I
took rdf for last bead of tails together that the first
part of file is as:</div>
0 0<br>
0.002 0<br>
0.004 0<br>
0.006 0<br>
0.008 0<br>
..............................0<br>
..............................0<br>
..............................0<br>
0.414 0<br>
0.416 0<br>
0.418 0<br>
0.42 0<br>
0.422 0<br>
0.424 0<br>
0.426 0.0577916<br>
0.428 0<br>
0.43 0.113443<br>
and maximum g(r) is in 0.512 nm (the first peak) and in
distance 0.47 nm, g(r) is 50.3262. Can I interpret that
tails are in two states together: bonded and non-bonded
but maximum of tails are non-bonded, therefore, there is a
hole in the center of micelle?<br>
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<br>
I don't know, but some well-chosen use of g_rdf or g_density might
get the information you seek if it's there to be found. Make sure
you visualize the simulation first.<br>
<br>
Mark<br>
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