I want to simulate the process of heterogeneous nucleation (containing ions (40 na+)) of supersaturated water vapor, and PPPM is used to compute the long-range coulombic interactions.
Thus, net charge of my simulation system is not zero, there is a warning in lammps: system is not charge neutral, net charge=40.
I do not know whether the result is available if I ignore the warning? What should I do? Does lammps can accurately simulate the system which is not charge neutral?
I will appreciate if you can give me some suggestions!
You should not ignore the warning.
Physically it does not make sense to simulate a periodic system with non-zero charge density.
You need to add negative ions to your system (Cl-) until the net charge is 0.
This should be easy to do (see below)
Andrew
P.S.
If you are using one of these water models: TIP3P, TIP4PEW, or SPC/E, then you can find the Lennard-Jones parameters for both Na+ and Cl- in
Joung & Cheatham JPCB (2008) http://pubs.acs.org/doi/abs/10.1021/jp8001614
The full example (with README files and pictures) can be downloaded with the examples at moltemplate.org. (It is in the folder examples/waterSPCE+Na+Cl/
/all_atom_examples/force_field_explicit/waterSPCE+Na+Cl)/
(Several other simple water models are in the “common” subdirectory, and it’s not hard to add your own.)
