4
One way could be as follow.
Download software PACKMOL.
Download the examples files (tar.gz or zip).
Modify the file solvprotein-comment.inp: removing the info about the protein, and the ions and define the number of water molecules and the size of the droplet:
#
# Protein solvated by water and ions
#
# All atoms from diferent molecules will be at least 2....
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