[gmx-users] how to convert CHARMM force constant into Gromos force field?
David van der Spoel
spoel at xray.bmc.uu.se
Wed Mar 23 17:06:24 CET 2005
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
> tokyo institute technology
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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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