>Date: Wed, 24 Sep 2008 10:15:44 -0700
>From: "Chih-Ying Lin" <[EMAIL PROTECTED]>
>Subject: [gmx-users] Forming a micelles
>To: [EMAIL PROTECTED]
>Cc: [email protected]
>Message-ID:
> <[EMAIL PROTECTED]>
>Content-Type: text/plain; charset=ISO-8859-1
>
>Hi
>Would you please say more about your system?
>How do you design / decide your simulation size of 100 surfactants +100
>co-surfactants + 4000 water molecules??
>
>How many surfactants will form a micelle?
>How many atoms does one surfactant have?
>How many atoms does one co-surfactant have?
>
>Do you start from the critical micelle concentration?
>You mentioned that it took 3 x 600 ps to see the micelles.
>Do you mean that you have 3 computers to do the parallel simulation?
>
>How long does it take to simulate 600 ps?
>Do you visualize the whole 600 ps-image and SEE the micelle?
>Or, other technique to KNOW the surfactants forming the micelles
>without visualizing the system?
>
>Thank you
>Lin
>
>******************************************
Dear Lin,
I have a suggestion:
Micelles should (theoretically) form above the CMC. So if you want a micelle,
the concentration should be >>CMC
I suggest that you find the CMC experimentally, then convert the concentration
to nm^3 (let say: mv/1000nm^3)
The number of molecules should be able to obtained by multiplying with Avogadro
number: (6.023x10^23). If your system contain co-surfactant, then you'll need
to get the experimetal CMC for at least one of the two surfactants.Take a look
at this paper:
Bourov G. K. and Bhattacharya A., Brownian dynamics of mixed surfactant
micelles, Journal of Chemical Physics, 123 (2005) 204712(1)-204712(6)
How long 600 ps simulation is depends on your system size, box type, parameters
and computational power (see manual).
One other way to KNOW the surfactants formed micelle is by measuring the
surface tension (use g_energy). But g_energy gives surface*surface tension
value, so you'll need to work on that. (HINT: Surface tension value drop
drastically at CMC)
Hope these helps,
Muhammad Alif Mohammad Latif
Department of Chemistry
Faculty of Science
Universiti Putra Malaysia
43400 UPM Serdang, Selangor
MALAYSIA
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