[gmx-users] Changing Sigma in force field

[hosein geraili]

Dear all,I am trying to change the epsilon of one atom type in the Amber force field, and because I have some atom in this type that I don't want to be changed, I defined a new atom type. I mean I add in all the files in the force field.ff directory that has that atom type a new atom type with a new name and new value for Sigma, but all the other thing are the same for this new atomtype, and then changed the aminoacids in the aminoacids.rtp file that I want to implement this change the atom type to this new one. But it doesn't work when I test it with one step MD for one aminoacid and one water. I also checked and if I change the value of Sigma for the already defined type the test answers properly. What am I missing here???Best