Dear All, I have a little confusion with the non-bonding parameters conversion from OPLS-AA to CHARMM in gromacs. If I see the ffnonbonded.itp in both the cases I get the following numbers
OPLS-GROMACS Sigma = 0.1644471 nm Epsilon = (0.875044*4.184) = 3.66118 kJ/mol ................................................................................................................................................................. CHARMM-GROMACS Sigma = 0.21114299 nm Epsilon = 0.06276 kJ/mol Now, from the charmm27 parameters file I get CHARMM27 Rmin/2 = 1.18500 Ang Epsilon = -0.0150 kcal/mol Converting these charmm parameters to gromacs formate I have to do following conversions Sigma = 2^(5/6) * (Rmin/2) = 2^(5/6) * 1.185 = 2.1114299 Ang = 0.2114299 nm Epsilon = 0.0150 * 4.184 = 0.06276 kJ/mol .................................................................................................................................................................... So, CHARMM (par_water_ions.prm) to charmm(ffnonbonded.itp) is fine. But the problem I'm facing to convert the OPLS(ffnonbonded.itp) to CHARMM(ffnonbonded.itp). I apologize for making any confusion. Thanks, Tarak -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! * Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
