meaning of atype in compute ti

Dear LAMMPS developers,

I’m trying to use compute ti to calculate the hydration free energy. I’m some confused about the meaning of the atype. In the manual for compute ti, there is only one sentence “To perform this calculation, you provide one or more atom types as atype.” But it does not say what atype means. I also looked for the answers from the mailing list, and someone asked this question, but without being answered. So could anyone tell me the meaning of atype?

Thanks,
Jibao

Dear LAMMPS developers,

I'm trying to use compute ti to calculate the hydration free energy. I'm
some confused about the meaning of the atype. In the manual for compute ti,
there is only one sentence "To perform this calculation, you provide one or
more atom types as atype." But it does not say what atype means. I also
looked for the answers from the mailing list, and someone asked this
question, but without being answered. So could anyone tell me the meaning
of atype?

​just look at the top of the documentation:

​pair style args = atype v_name1 v_name2
  atype = atom type (see asterisk form below)

​axel.​

Hi Axel,

Thank you for your answer. Yes, I knew that atype is atom type. But I’m confused about the meaning of specifying an atom type here.
If I have 4 types of atom 1,2,3,4 in my simulation system and I set the atype as 1, does it mean the compute ti only considers the interactions that involve atom 1, while other interactions between atom 2, 3, 4 are not considered in calculating du/dlambda?

Thanks,
Jibao

Hi Axel,

Thank you for your answer. Yes, I knew that atype is atom type. But I'm
confused about the meaning of specifying an atom type here.
If I have 4 types of atom 1,2,3,4 in my simulation system and I set the
atype as 1, does it mean the compute ti only considers the interactions
that involve atom 1, while other interactions between atom 2, 3, 4 are not
considered in calculating du/dlambda?

​have you read the paper referenced in the documentation. please note that
the LAMMPS documentation for the individual commands will tell you how a
feature is operated, it is no replacement for learning the underlying
methodology and theory. ​the answer to this question should be self-evident.

axel.