Really sorry for the carelessness.
I am really appreciate for your kindly help, axel.

My choice for the cutoff of atom CC is just the case one you have
said(sigma*2^(1/6)), cause the strong attractive force between atom CC
will have big influence on the simulation result. But as what you have
said, this result perhaps the truthful one. But I want to overcome the
high energy barrier of CC and see what will happen. So I was wondering
is there a convinient method to achieve the following 2 requirement:

1.For atom pair AA AB AC and BB BC, the lj cutoff is the largest
global cutoff as what you recommend
2.and for atom pair CC, the lj cutoff distance is sigma*2^(1/6) as the
case one you have said.

Sorry for not having explaining the R1,R2 in my last email.And to
achieve this, I have figured out two method, I was wondering which
method can achieve what I want?
Really appreciate for your kindly help:

Really sorry for the carelessness.
I am really appreciate for your kindly help, axel.

My choice for the cutoff of atom CC is just the case one you have
said(sigma*2^(1/6)), cause the strong attractive force between atom CC
will have big influence on the simulation result. But as what you have
said, this result perhaps the truthful one. But I want to overcome the
high energy barrier of CC and see what will happen. So I was wondering
is there a convinient method to achieve the following 2 requirement:

1.For atom pair AA AB AC and BB BC, the lj cutoff is the largest
global cutoff as what you recommend
2.and for atom pair CC, the lj cutoff distance is sigma*2^(1/6) as the
case one you have said.

Sorry for not having explaining the R1,R2 in my last email.And to
achieve this, I have figured out two method, I was wondering which
method can achieve what I want?

i don't quite understand your reasoning for your choices and also i am