Greetings, I am trying to use tabulated potentials for the VdW interactions between TIP5P water molecules. I have tested my topology file to make sure that it gives reasonable results with the standard table6-12.xvg in the /top folder and C6=4*eps*sig^6 , C12=4*eps*sig^12. I am able to match the energies with an identical run not using look-up tables. The problem comes when I want to include the C6 & C12 parameters within the table. This is needed for dealing with more complex multi-parameter potential functions.
I tried testing this with the standard Lennard-Jones potential. Setting g(r)=-(4*eps*sig^6)/r^6 and h(r)=(4*eps*sig^12)/r^12. I then construct my table according to [r,f(r),-f'(r),g(r),-g'(r),h(r),-h'(r)] I set vdw-type = user in my mdp file and modified my topology so that: [ defaults ] ; nbfunc comb-rule gen-pairs fudgeLJ fudgeQQ 1 1 yes 0.5 0.8333 [ atomtypes ] ; name at.num mass charge ptype C6 C12 OW_tip5p 8 16.00 0.0000 A 1.00000e+00 1.00000e+00 Since C6 & C12 = 1, this run should be identical to using the table6-12.xvg and C6=4*eps*sig^6 , C12=4*eps*sig^12 The run proceeds fine with no warnings or errors, but the LJ and Potential energies are an order of magnitude higher than when using the standard table. I don't understand why I am not able to reproduce the results by this method? Thanks, Andrish -- View this message in context: http://gromacs.5086.x6.nabble.com/C6-C12-parameters-for-non-bonded-interactions-using-tables-tp5008449.html Sent from the GROMACS Users Forum mailing list archive at Nabble.com. -- 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
