Negative pressure

Hi all,
       I am new to LAMMPS and i am trying to perform to minimize water molecules.
In the output listed while minimizing, i found that the pressure is having a negative value.
I tried to perform some NVT simulations also. Still the pressure term displays a negative value.
Could you please kindly let me know why is it. Herewith i have attached my input script.
Kindly let me know what can i do.

#Lammps Input script for water
units real
dimension 3
newton on
processors * * *
boundary p p p

#Defining different potential types
atom_style full
pair_style lj/cut/coul/long 10.0 9.0
bond_style harmonic
angle_style harmonic

read_data water.lammps05
#read_restart restart_water.300
kspace_style ewald 0.01
dielectric 1.0

#Data reading and neighbouring
neighbor 2.0 bin
neigh_modify every 1 delay 0 check yes


min_style cg
minimize 1.0e-6 1.0e-8 500 1000

timestep 1.0
fix 1 all nvt temp 300.0 300.0 10.0
#fix 2 all temp/berendsen 300.0 300.0 100.0 # Not Necessary when NVT is used
dump 1 all xyz 100
thermo 100
thermo_style multi
run_style verlet
run 1000
#write_restart restart_wate-dyn.300


Pressures can be negative or positive. A negative
pressure typically means that if you allowed the system's
volume to change (e.g. fix npt) then it would want to
shrink to come to zero pressure.