Hi Paul and Steve, Thanks for your help. I also have another system with
3611 water molecules in them. I have the set points for the thermostat and
barostat to 300 K and 1 atm respectively. I ran up to 100 pico seconds
with an equilibration of 10 pico seconds before gathering data. These are
the average thermo properties:
P: 3.76896 +- 346.655 atm
T: 300.042 +- 4.51091 K
V: 111944 +- 404.135 A^3
The V corresponds to a density of 0.964 g/cc which is pretty much close to
water. I got the 300 K set point for the temperature however you can see
that the P fluctuation is high with a std. dev of 346 atm.
Is this normal? How many water molecules should I have so that these
fluctuations will decrease? I didn't see this problem when I was running
lj systems with the same number of particles in them. P was pretty much
constant in LJ/coarse grain systems.
I foresee that I cannot use the sxx,syy and szz atom stress tensor dumps
to compute surface energy in an oil and water interface system. Any
comment on this is highly appreciated.