Hello, I've been trying some time now to run a QMMM calculation with gromacs and orca on a system of 5000 atoms with the QM system being ~300 atoms.
Setting up the calculation with bOpt = yes and 1 minim step in the .mdp file produces some problems. Orca does the calculation without taking into account the LJ coefficients. The .LJ file should be generated by gromacs prior to the calculation so Orca uses it for the QM atoms optimization right? ( I have seen that there should be LJ and LJ.Excl files) However these files are not generated and Orca does a "perfect" optimization of 300 cycles but without taking into account any Lennard Jones input. So in every optimization step Orca skips VdW correction (No LJ-filename given... skipping VDW correction) because it doesn't find the LJ file and continues the QM optimization in the absence of the MM system. I am running gromacs 4.5.5 and after many many tries, I cannot see the .LJ file. Not in the beginning, nor during the calculation in the woking directory. Could there be an explanation why gromacs does not generate this file? Best Minos I attach my mdp file: ------------------------- title = Yo ; a string cpp = /lib/cpp ; c-preprocessor integrator = cg ; ;integrator = l-bfgs rlist = 1.0 ; cut-off for ns rvdw = 1.4 ; cut-off for vdw rcoulomb = 1.5 ; cut-off for coulomb ; Energy minimizing stuff ; nsteps = 1 emtol = 100 emstep = 0.1 nstxout = 1 nstfout = 1 nstlog - 1 nstvout = 1 nstxtcout = 1 nstenergy = 1 QMMM = yes QMMM-grps = QMatoms QMMMscheme = ONIOM QMbasis = 6-31g* QMmethod = RHF QMcharge = 1 QMmult = 1 bOpt = yes and ORCAINFO file: ------------------------ ! RHF 6-31g* SV(P) moread %moinp "orbitals.gbw" %pointcharges "charges.pc" %pal nprocs 24 end and the .inp file Orca needs that is generated by gromacs: -------------------------------------------- #input-file generated by gromacs !QMMMOpt TightSCF ! RHF 6-31g* SV(P) moread %moinp "orbitals.gbw" %pointcharges "charges.pc" %pal nprocs 24 end %geom . . . . . -- View this message in context: http://gromacs.5086.n6.nabble.com/Gromacs-Orca-QMMM-LJ-coefficients-problem-tp4999490.html Sent from the GROMACS Users Forum mailing list archive at Nabble.com. -- gmx-users mailing list [email protected] http://lists.gromacs.org/mailman/listinfo/gmx-users * Only plain text messages are allowed! * 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 [email protected]. * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
