Hi all<br><br>I am trying to simulate 150 molecules of hexane in a triclinic box (8.319*3.01*3.01 nm^3) using OPLSAA force field.I got the .gro file from PRODRG and generated the topology using X2top command. when i run energy minimisation for hexane my potential energy is positve. is this right?. what i should correct to get the potential energy as negative. below is my result. any help is highly appreciated.<br>
<br>Steepest Descents converged to Fmax < 100 in 10454 steps<br>Potential Energy = 3.4133051e+04<br>Maximum force = 9.8812309e+01 on atom 635<br>Norm of force = 7.9230022e+00<br><br>Below is my contents of my em.mdp file<br>
<br>integrator = cg <br>emtol = 100.0 <br>emstep = 0.01 <br>nsteps = 50000 <br>nstcgsteep = 1000<br>nstlist = 1 <br>ns_type = grid <br>
rlist = 1.0 <br>coulombtype = PME <br>fourierspacing = 0.12<br>rcoulomb = 1.0 <br>rvdw = 1.0 <br>pbc = xyz <br><br>Regards<br>Vinoth <br><br>