From: faride badalkhani (farideh.khamseh_at_gmail.com)
Date: Fri Mar 18 2016 - 11:23:39 CDT
Thanks a lot dear Josh. I want to simulate a hyperbranched polymer and I
have some problem with charge assignment. which one do you recommend:
1) performing ab initio calculations to find atomic charges or
2) using the atomic charges near to my structure from CHARMM 36 topology
file (I am using this FF)?
Truly yours,
Farideh
On Fri, Mar 18, 2016 at 7:40 PM, Josh Vermaas <vermaas2_at_illinois.edu> wrote:
> Hi Farideh,
>
> Charge groups should be integers, and used to be mandatory before PME took
> care of long range electrostatics, since they were used to make sure that a
> dipole didn't get split across a cutoff-boundary. Now they are just nice to
> have, but I don't believe they are mandatory.
>
> -Josh Vermaas
>
>
> On 03/18/2016 10:56 AM, faride badalkhani wrote:
>
> Dear all,
>
> I need to know if it is mandatory to define charge groups in residues?
> and if it is, should total charge of each charge group be equal to zero?
>
> any help will be appreciated.
>
> Truly yours,
> Farideh
>
>
>
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