[gmx-users] nrexcl value for ions

[Justin Lemkul]

On 1/3/20 12:10 AM, Dhrubajyoti Maji wrote:
> Dear gromacs users,
>       A very happy new year to all of you. I an trying to simulate LiBr and
> LiNO3. What will be the value of nrexcl in OPLS itp file for respective
> cation and anions? I found nrexcl=1 for atomic ions in ions.itp file in
> gromacs. Again in a tutorial of simulation of Choline Chloride + urea, they
> have used nrecxl=3 for chloride ion. Here, I am confused about this. Any
> kind of help will be highly appreciated.

There are no covalent bonds in monoatomic ions, so any value of nrexcl 
can be used. NO3 has a maximum of two contiguous covalent bonds so 
nrexcl = 2. Or you can set nrexcl = 3 for everything, which has the 
exact same effect.

-Justin

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Justin A. Lemkul, Ph.D.
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