Contradiction using Tersoff in LAMMPS !!!

Dear LAMMPS users,

For my system, in tersoff file for Si N Si I have the following line:

Si N Si 3.0 1.0 0.0 1.0039e5 16.217 -0.59825 0.78734 0 0 0 2.85 0.1499999999999999 0 0

According to my understanding when A and Lambda1 is zero ( Which means f-R is zero), and B is zero ( which means f-A is zero), then f-R and f-A is zero. Therefore, there is no difference when I change other components of the aforementioned line as the total potential shouldn’t change. Surprisingly, in my system it is not like that. For instance, when I change R for example at the line, pressure components change. Is it a software mistake or there is something else or I missed any thing ?