Good morning everybody,
I am simulating CO2 diffusion in water (epm2 and SPCE) and I get completely different results with pppm and ewald. My scripts and data files are completely identical with the only difference in the k space command.
Basic input scheme:
units real
atom_style full
boundary p p p
read_data 1000spc_5epm2.data
pair_style lj/cut/coul/long 12
kspace_style ewald 1.0e-4 or pppm 1.0e-4
pair_modify tail yes
LJ parameters e and sigma for spc water
pair_coeff 3 3 0.1553 3.166
pair_coeff 4 4 0.0 0.0
pair_coeff 3 4 0.0 0.0
LJ parameters for EPM2 CO2
pair_coeff 1 1 0.0559 2.757
pair_coeff 2 2 0.1599 3.033
pair_coeff 1 2 0.0946 2.892
LJ cross molecule interactions
pair_coeff 1 3 0.0932 2.9615
pair_coeff 2 3 0.1576 3.0995
pair_coeff 1 4 0 1.3785
pair_coeff 2 4 0 1.5165
group co2 type 1 2
group water type 3 4
timestep 1.0
neighbor 1.0 bin
neigh_modify delay 1 check yes
velocity all create 323.15 12345 dist gaussian
fix npt all rigid/npt molecule temp 323.15 323.15 200.0 iso 0.9869 0.9869 1000.0
thermo 10000
thermo_modify flush yes
run 1000000
#run 1000000
#run 1000000
#run 1000000
write_restart equilib.restart