[gmx-users] how to convert CHARMM force constant into Gromos force field?

[David van der Spoel]

On Thu, 2005-03-24 at 01:01 +0900, コウ チ wrote:
> hell all:
>   
>   i want to change some bonds force constants and bond lengths to do some 
> simulations. it seems that can be done by modifing FFg43a1bon.itp.
>   The CHARMM force field which i used before defined the force constant 
> with physical units Kcal/mol/A*A which almost in 10^2  orders. ( for 
> example the force constant of C-C is 240 ).
> but in the FFg43a1bon.itp most force constant is in 10^(-7) orders ( for 
> example : #define gb_1        0.1000  1.5700e+07
> ; H  -  OA      750                    )
>  From the Gromacs manual it seems that the pysical units of force constant 
> is KJ/mol/nm*nm
> .even that i think the order is too far from that of CHARMM. so how to 
> convert CHARMM force constant into Gromos force field?
look in the manual under g96bonds

> 
> rgards
>                                                                        
> caoch
>                                                                        
> tokyo institute technology
> 
> 
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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://xray.bmc.uu.se/~spoel
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