when we set the .nwchemrc file, we should define like follows:
amber_1 /some directory/amber_s
amber_2 /some directory/amber_q
amber_3 /some directory/amber_x
I think here "1" "2" and "3“ refer to the "set 1" "set 2" and "set 3". I guess, "initial" means "set 1" and "final" means "set 3", if the definitions are same as above.