[gmx-users] charmm27 in gromacs

[Peter C. Lai]

In a nutshell, yes dihedral type 2 is for the IMPR charmm dihedrals and
9 is for the normal dihedrals. I think David or someone else added code to
specifically support charmm dihedrals in this way.

On 2012-02-14 09:32:37PM -0600, Tom wrote:
> Dear Gmx Developer or Users,
> 
> Can anyone explain which section is for  the parameters of improper
> dihedral angle
> on the file of ffbonded.itp ?
> 
> On the file of ffbonded.itp, there is not any comment to differentiate the
> proper and improper
> dihedral angle.
> 
> E.g. on thie file of ffbonded.itp in the directory of charmm27.ff
> There are two sections about dihedral angle:
> 
> [ dihedraltypes ]
> ; i     j       k       l       func    phi0    cp      mult
> C       CT1     NH1     C      * 9*       180.00  0.8368  1
> ......
> 
> [ dihedraltypes ]
> ; i     j       k       l       func    q0      cq
> CPB     CPA     NPH     CPA    * 2*       0.0000  174.0544
> ..........
> There is also no explaination the explaination about the function type 2.
> 
> It seems difficult for users to edit the parameters.
> Thanks for the explainations!

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Peter C. Lai			| University of Alabama-Birmingham
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