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#37676 - 10/03/19 01:41 PM Generating CHARMM Force Field Outputs
N Quartey Offline
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Registered: 10/01/19
Posts: 1
Hi All,

We are using a global and local minima search program for chemical cluster geometries called ABCluster. The input parameters to run ABCluster require that we specify q, epsilon, and sigma for each atom. These parameters are obtained using CHARMM. The ABCluster program provides some output files that were obtained using CHARMM36 and contains the input parameters needed (see attached example file) to run ABCluster. We have been trying to replicate these files using CHARMM, but we haven't been able to do so. Could you provide information on how to obtain similar files with CHARMM?

Thank you in advance!


Attachments
h2so4.txt (547 downloads)


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#37677 - 10/03/19 03:08 PM Re: Generating CHARMM Force Field Outputs [Re: N Quartey]
rmv Online   content

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Registered: 09/17/03
Posts: 8407
Loc: 39 03 48 N, 77 06 54 W
The atom charges are in the topology files (.rtf), and L-J values are in the parameter files (.prm). The L-J epsilon values are in kcal/mol; instead of sigma, Rmin/2 values are used.

I am not certain that there is an H2SO4 residue in the force field, although there are sulfates as pendant groups, and also CH3SO4- anion.
_________________________
Rick Venable
computational chemist


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