Hi all,

I'm currently trying to simulate an interface system between water and epoxy. I constructed a box with a layer of epoxy at the bottom and a layer of water molecules as well as Na+ and Cl- ions on the top. I used COMPASS III forcefield for the whole system and ran geometry optimization. However, I found that after the optimization, some of the Cl- atoms form bonds with other H2O molecules. I also saw two H2O molecules bonded together between H atoms. I don't know why that happened and please can anyone help me with this issue? Thank you! Below are the figures of the system before and after optimization process. And you can see the bonds between Cl- and H2O on the second picture.