Re: What is an IC table in the .inp files

From: Richard Wood (rwoodphd_at_yahoo.com)
Date: Fri Nov 16 2007 - 13:46:26 CST

Hi Ilya,

For topology files, go to: http://www.charmm.org/document/Charmm/c32b2/rtop.htmlFor parameter files, go to: http://www.charmm.org/document/Charmm/c32b2/parmfile.html

Richard

Richard L. Wood, Ph. D.
University of Minnesota
Dept. of Medicinal Chemistry,
College of Pharmacy
717 Delaware St. SE
Minneapolis, MN 55419-2959
rwoodphd_at_yahoo.com

----- Original Message ----
From: Ilya Chorny <ichorny_at_gmail.com>
To: Richard Wood <rwoodphd_at_yahoo.com>
Cc: NAMD list <namd-l_at_ks.uiuc.edu>
Sent: Friday, November 16, 2007 1:31:44 PM
Subject: Re: namd-l: What is an IC table in the .inp files

Can you show me where in the Charmm website is the information on
topology files.

I still do not understand the difference between the internal
coordinates and the definitions in the par files.

Thanks,

Ilya

On Nov 15, 2007 7:29 PM, Richard Wood <rwoodphd_at_yahoo.com> wrote:
>
> IC stands for "Internal Coordinates", which are used to define bond
 lengths,
> bond angles, dihedrals and improper dihedrals. These are listed as
 part of
> each topology, and each dihedral must be defined, otherwise the
 energies
> will not be calculated correctly.
>
> The .par file is the PARAMETER file, which tells you bond length,
 angle and
> dihedral values for various atom types. The topologies are read from
 the
> .inp file, so that each file is necessary. Just because something
 (ie, a
> dihedral) is listed in the topology file NAMD (or CHARMM) still
 requires a
> parameter file.
>
> I'd recommend checking out www.charmm.org for documentation about the
> topology and parameter files.
>
> Richard
>
> Richard L. Wood, Ph. D.
> University of Minnesota
> Dept. of Medicinal Chemistry,
> College of Pharmacy
> 717 Delaware St. SE
> Minneapolis, MN 55414-2959rwoodphd_at_yahoo.com
>
>
>
>
> ----- Original Message ----
> From: Ilya Chorny <ichorny_at_gmail.com>
> To: NAMD list <namd-l_at_ks.uiuc.edu>
> Sent: Thursday, November 15, 2007 8:02:07 PM
> Subject: namd-l: What is an IC table in the .inp files
>
> Hi All,
>
> I am working on porting a third party lipid forcefield to NAMD
 format.
> When looking at the POPE forcefield in CHARMM27 (all_27***) there is
 a
> something called an IC table which looks like a definition of
 dihedral
> potentials. Is that correct? Also what is the relationship between
 the
> .par and .inp files. Does NAMD default to the definition in the .inp
> file prior to looking up up the values in the .par file. For example
> if the IC table is the definition of the dihedral potential would
 namd
> use those definitions and ignore what is in the .par file?
>
> Thanks,
>
> Ilya
>
>
> --
> Ilya Chorny Ph.D.
>
>
>
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