[gmx-users] Reg: Energy minimisation of hexane

[vinothkumar mohanakrishnan]

Hi all

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.

Steepest Descents converged to Fmax < 100 in 10454 steps
Potential Energy  =  3.4133051e+04
Maximum force     =  9.8812309e+01 on atom 635
Norm of force     =  7.9230022e+00

Below is my contents of my em.mdp file

integrator        = cg
emtol             = 100.0
emstep          = 0.01
nsteps           = 50000
nstcgsteep     = 1000
nstlist             = 1
ns_type          = grid
rlist                = 1.0
coulombtype   = PME
fourierspacing = 0.12
rcoulomb        = 1.0
rvdw              = 1.0
pbc               = xyz

Regards
Vinoth
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