[gmx-users] Frozen groups lead to a high energy
samdav800 at gmail.com
Fri Nov 30 00:24:04 CET 2018
Dear gromacs users
I'm simulation a hydrocarbon and water mixture placed on a slab of metal.
The metal surface is frozen in the z-direction. Energy minimization works
with no errors but I see the potential energy is too high as below.
Steepest Descents converged to machine precision in 1754 steps,
but did not reach the requested Fmax < 1.
Potential Energy = 1.9604517e+08
Maximum force = 3.1745122e+03 on atom 23433
Norm of force = 3.8078518e+01
After energy minimization, I did short nvt followed by short npt then npt
production. I tried several times and different parameters to reduce the
energy of the system but still very high as below:
Bond Angle Proper Dih. Ryckaert-Bell. Improper Dih.
2.07807e+08 2.96662e+05 8.57456e+02 2.50326e+04 1.60567e+02
LJ-14 Coulomb-14 LJ (SR) Disper. corr. Coulomb (SR)
4.33776e+04 -7.73429e+03 3.05165e+11 -1.07225e+04 -1.24055e+07
Coul. recip. Potential Kinetic En. Total Energy Temperature
5.93613e+03 3.05360e+11 1.97149e+05 3.05361e+11 3.88708e+02
Pres. DC (bar) Pressure (bar) Constr. rmsd
-2.71515e+02 3.08812e+10 4.72857e-06
However, when I remove frozen groups, potential energy becomes negative
Any ideas on how to reduce system energy while using freeze groups option!
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