[gmx-users] Analytic first derivatives with respect to parameters?

[David van der Spoel]

Lee-Ping wrote:
> Hi there,
> 
> I'm trying to modify the GROMACS source code to obtain analytic
> derivatives of the energy and the force with respect to the force field
> parameters.  The goal of this is to help improve force field fitting /
> optimization routines.  Before I begin, has this already been done by
> anyone?  If not, can someone give me a tip on where to actually declare
> the new variable (say, dE/dk where E is the energy and k is the force
> constant)?
> 
check out:
- P. J. van Maaren and D. van der Spoel: Molecular Dynamics Simulations 
of Water With Novel Shell-Model Potentials J. Phys. Chem. B. 105 pp. 
2618-2626 (2001
- David van der Spoel, Paul J. van Maaren and Herman J.C. Berendsen: A 
systematic study of water models for molecular simulation: Derivation of 
water models optimized for use with a reaction field. J Chem Phys 108 
pp. 10220-10230 (1998)

in addition there is a bit more along these lines in the program ffscan 
but not exactly what you are indicating.
On the other hand FEP calculations do compute these, for instance 
changing a force contant from A->B you will get the analytical energy 
derivative. See manual and relevant references therein.

> Thanks a lot!
> 
> - Lee-Ping Wang
> 
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-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://folding.bmc.uu.se
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