[lammps-users] MEAM or Tersoff potentials

Hi everybody,

I am new to lammps. At the moment I am studying some of the examples and looking at the guide in order to understand how it works. There is something, however, that is puzzling me. In some of the command examples in the guide (e.i. pair_style meam or tersoff or hybrid) there are phrases like:
"if your lammps simulation has 4 atom types and you want the 1st 3 to be Si and the 4th to be C you should use the pair_coeff command: pair_coeff * * library.meam Si C sic.meam Si Si Si C".

There is probably something fundamental of lammps I am missing, because I do not understand why should I declare 4 atom types (in the data file I suppose) if three of them are the same.

Can you help me in understanding this point?

Another issue. I do not know what I am doing wrong, but when I try to search for a specific entry in the lammps mailing list archive I usually do not find anything or only a few post. When I browse "by hand" I find many entries that should have found with the search option. I am using the little menu "Forum-->Search" on the top of the page. Is there any other way?

Thanks in advance

Alessio

There is probably something fundamental of lammps I am missing, because I do not understand why should I declare 4 > atom types (in the data file I suppose) if three of them are the same.

People use atom types for things other than identifying the element. A model
might have mobile Si atoms as type 1, and wall Si atoms as type 2.

Another issue. I do not know what I am doing wrong, but when I try to search for a specific entry in the lammps mailing list archive I usually do not find anything or only a few post. When I browse "by hand" I find many entries that should have found with the search option. I am using the little menu "Forum-->Search" on the top of the page. Is there any other way?

You should be searching the mail lists, not the forums, which are
different entities on SForge.
The SF search sometimes just doesn't work. If someone could tell me
how to extract
the LAMMPS mail archive from SF and put it somewhere like Google
Groups, I'd probably
do it. In my experience SF has lots of problems and zero support.

Steve