AMBER Archive (2004)

Subject: Re: AMBER: Does this warning matter? (about improper torsion parameters)

From: David A. Case (case_at_scripps.edu)
Date: Wed May 19 2004 - 10:00:59 CDT

On Wed, May 19, 2004, J. Zhang, Dr wrote:
>
> When I tried to create topology file by using tleap,
> I found there are some warning in the leap.log file,
> such as:
> --------------------------------------------------------
> Building proper torsion parameters.
> Building improper torsion parameters.
> ** Warning: No sp2 improper torsion term for C*-CN-CB-CA
> atoms are: CG CE2 CD2 CE3
> ** Warning: No sp2 improper torsion term for NA-CA-CN-CB
> atoms are: NE1 CZ2 CE2 CD2

These are OK: they are torsions about the ring fusion atoms in TRP, and
the force field designer (==me) decided that it was not necessary to have
impropers about these atoms, even though most sp2 atoms do have impropers,
hence the warning when you set your verbosity level up.

...regards...dac 

-- 

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David A. Case                     |  e-mail:      case_at_scripps.edu
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