[gmx-users] Re: Improper angle value

[Anton Feenstra]

Alexander wrote:
> Hi Anton,
> 
> I have check my calculations of improper torsion of formaldehyde
> manually. Obtained value is 1.329 as reported before.
> The details are attached.
> So would you please to comment the gromacs calculation scheme and
> significant differences in obtain energies? I need it for QM-based
> automatic parameterization tool, and now I don't know how to compare
> the conformers energies of QM and gromacs calculations to reproduce QM
> molecular behavior in gromacs.

The Gromacs forcefields and interaction functions are described in the
manual and implemented identically. Otherwise, you might check the source,
but I can't tell you from the top of my head in which file(s) you should look.

By the way, conformational energies in a forcefield are almost by definition not
comparable to QM energies - they are simply completely independent properties.

Futher than that, I have just used a simple method to verify your angle,
if you are sure about your calculation, feel free to disregard my value.


-- 
Groetjes,

Anton
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|  _   _  ___,| K. Anton Feenstra                                     |
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