Hi All, I am simulating molten urea (contains only urea molecule) at 406 K. After the energy minimization, I found the potential energy positive (~10^4 ).
Steepest Descents converged to Fmax < 100 in 646 steps Potential Energy = 3.8694098e+04 Maximum force = 8.9818977e+01 on atom 26 Norm of force = 2.2291134e+01 I have used these potential parameters of urea previously for simulating acetamide+urea mixtures which gives results matching closely with the experimental ones. Please see below my input file: ; minim.mdp - used as input into grompp to generate em.tpr ; Parameters describing what to do, when to stop and what to save integrator = steep ; Algorithm (steep = steepest descent minimization) emtol = 100.0 ; Stop minimization when the maximum force < 50.0 kJ/mol/nm emstep = 0.001 ; Energy step size nsteps = 10000 ; Maximum number of (minimization) steps to perform ; Parameters describing how to find the neighbors of each atom and how to calculate the interactions nstlist = 2 ; Frequency to update the neighbor list and long range forces ns_type = grid ; Method to determine neighbor list (simple, grid) rlist = 1.3 ; Cut-off for making neighbor list (short range forces) coulombtype = PME ; Treatment of long range electrostatic interactions rcoulomb = 1.3 ; Short-range electrostatic cut-off rvdw = 1.3 ; Short-range Van der Waals cut-off pbc = xyz ; Periodic Boundary Conditions (yes/no) Can you suggest me what should I do to overcome the potential energy problem? regards, Suman -- Suman Das Senior Research Fellow, Dept. of Chemical Biological and Macromolecular Sciences S.N.Bose National Centre For Basic Sciences, Block-JD, Sector-III, Salt Lake City Kolkata-700098, India -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to [email protected].
