Hi all,
I have a problem when I tried to do NVE simulation in an organic system. From the manual, the total energy should be conservative under NVE, however in our case the total energy fluctuation was about 50~80kcal/mol for the system contains 98 atoms (two chains, each chain contains 5-ring thiophene with a –C3H6COOH group attached to it’s tail ). We also did tests such as more atoms and smaller tiemsteps, but there’s no apparent improvement. Follows are the main commands
initialization
units real
dimension 3
atom_style full
pair_style lj/class2/coul/long 10.0
bond_style class2
angle_style class2
dihedral_style class2
improper_style class2
boundary p p p
kspace_style ewald 1E-05
atom definition
read_data struct2.lammps05
settings
neighbor 2.0 bin
neigh_modify delay 0 every 1 check yes
timestep 1.0
min_style cg
neigh_modify every 2 delay 10 check yes one 10000 page 100000
run_style verlet
thermo 1
thermo_style custom step etotal temp pe ke
dump mydump all atom 1 dump.out
minimize 1.0e-11 1.0e-12 5000 10000
velocity all create 230 4928459 dist gaussian
fix 1 all nve
run 100000
unfix 1
We thanks very much for any suggestions!
Best,
Junfeng