Re: [gmx-users] Charge derrivation for OPLSAA forcefield

2012-05-09 Thread Dommert Florian
On Tue, 2012-05-08 at 11:38 -0700, Milinda Samaraweera wrote: 
 Hi Guys
 
 
 I was using the program http://q4md-forcefieldtools.org/RED/ to
 derrive ESP based charges for some molecules that I study. Is this a
 correct method to do so if not please let me know what are the other
 methods that are available.
 

Hi,

this is really a hard questions to answer. Different methods to derive
partial charges are present, which rely on various ideas. Actually, the
partial charges of a force field should be consistent, because they are
anyway just an approximation for the true charge density. Common force
fields like AMBER or OPLS-AA were constructed with different
consideration, giving rise to the differences, though they allow to
desribe the same molecules. So I would study, how the remaining
parameters of the applied force field were derived. Furthermore be aware
that altering a single charge of force field might require readaption of
dihedral and LJ parameters. Hence, always be careful and benchmark the
force field  against single as well collective static and dynamic
properties, carefully.

/Flo

 
 thanks alot
  
 Milinda Samaraweera
 University of Connecticut
 Department of Chemistry
 55 N Eagleville road
 unit 3060
 Storrs CT
 USA
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-- 
Florian Dommert
Dipl. - Phys.

Institute for Computational Physics
University Stuttgart

Pfaffenwaldring 27
70569 Stuttgart

EMail: domm...@icp.uni-stuttgart.de
Homepage: http://www.icp.uni-stuttgart.de/~icp/Florian_Dommert

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[gmx-users] Charge derrivation for OPLSAA forcefield

2012-05-08 Thread Milinda Samaraweera
Hi Guys

I was using the program http://q4md-forcefieldtools.org/RED/ to derrive ESP 
based charges for some molecules that I study. Is this a correct method to do 
so if not please let me know what are the other methods that are available.

thanks alot

 
Milinda Samaraweera
University of Connecticut
Department of Chemistry
55 N Eagleville road
unit 3060
Storrs CT
USA-- 
gmx-users mailing listgmx-users@gromacs.org
http://lists.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at 
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