Hi I am simulating a bilayer structure of decane oil-water with AOS surfactant presence at the interface. The middle water layer has a NaCl concentration of approximate 12.11 wt%. Force fields used is gromos54a7 as many research have cited this to be a good fit for my application. After the 30 ns production run I am observing that Na and Cl atoms has formed aggregates near the interface.
green and blue dots in the middle are Cl and Na)
I am not sure why this is happening. Has anyone found same result? How to solve this I am attaching my mdp file
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Hi Neetish
I’m attaching a paper that will help you to understand the problem you face and one way to solve this.
This problem (salt aggregation) is widely reported for force fields that use TIP3P, SPC water models and ions with electronic charge +-1 e, where very likely is your problem. You can read about this in the paper attached.
Also you can find that one way to fix the premature salt aggregation is to use the TIP4P/2005 water model and the force field developed in that work.
Maybe you would have to adjust by hand the interaction among components.
Good Luck!!
What is the ratio of the number of sodium ions to the number of water molecules? If the ratio is 1:55.5, the NaCl concentration is 1 M . . .
Wojciech Kopec
What I found this to be a problem of force field. Gromos is not designed to simulate at this concentration. One of the developer on gormacs forum said the same to me.Iván Michael Zerón thanks for the paprt
Martin Klvana Yes it is more than 1 M
The concentration of NaCl is high. You must verify this value. The water/NaCl ratio is bad. Gromacs allows us to determine the correct relationship between ions and water molecules
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