Thanks for your reply, Mubin.
I agree with you. What makes me wonder is that even if there existing repusion between top and bottom for system (a), most articles published are using it to simulate adsorption of gas molecules in clay slit pores. Further, the computation using system (a) would cost more machine hours because of more atoms in it. So, is it reasonable to replace (a) with (b) to research slit pore ?
Best regard.
Dongbo Wang
