[gmx-users] epsilon_r option

[HongTham]

Dear all,
I want to ask two questions about the epsilon_r and epsilon_rf option in
mdp file to run CG simulation.
If I do not specify 2 these option, the gromacs will return the default
value (epsilon_r = 1 and epsilon_rf = 0). If the epsilon_r =15, is there
any effect on the electrostatic interaction calculation? actually, I don't
know why many sample mdp file using this value. :"(

If the epsilon_rf is set to a value ( not = 0 ), it means there will be a
screening effect on the electrostatic calculation result, doesn't it? I
think it just be applied when run simulation with reaction field or
implicit MD simulation. However, I am running the explicit MD simulation, I
should not set epsilon_rf option, just let it be default value (= 0). Am I
right?

Thank you so much.
Hongtham