Keyword confusion: meaning of coulomb_subtract rmax and ewald realradius

Hi julian:
Just a silly question. What is the difference of coulomb_subtract rmax and ewaldrealradius? I set ewaldrealreadius to 9.0 angstrom ,but the result of real monopole energy of coulomb rmax 10.0 and 15.0 is 60.46 ev and 26.11 ev respectively.
ff0.lib (553 Bytes)
ff1.lib (553 Bytes)
single0.gin (1.9 KB)
single0.gout (12.5 KB)
single1.gout (12.5 KB)
single1.gin (1.9 KB)

The coulomb_subtract option removes the Coulomb interaction within a radius, whereas the ewaldrealradius controls the balance between real and reciprocal space in the Ewald sum, but doesn’t change the value of the Coulomb energy.

Thank you very much!
So in gulp I do not need to include coulomb potential in force field ,it will calculate coulomb interaction by default ?

If you have charges then the Coulomb interaction is indeed included by default.