Boundary conditions for Nanowries

Hi All

I imported geometry of a nanowrie using “read_data” and I set the limits of the box in all directions
( xlo xhi , ylo yhi, xlo zhi ). Then I did thermal conductivity calculations. My interest is to have infinite
length along the axis of the nanowire (z-direction) but I am having big doubts on what boundary conditions
to use. I dumped the geometry after equlibrating by using “p p p” BCs but the geometry got strange shape.
Using "s s s " BCs the general shape of the nanowrie is maintained but I am not sure if the infinite length
effect is maintained. I went through some of the discussions in the forum but I haven’t been convinced.
Some use "s s s " , “p p p”… ideas …comments will be of great help

Regards,
Z

Hi, you can look at this https://icme.hpc.msstate.edu/mediawiki/index.php/LAMMPS_Nanowire_Deformation, the 9th tutorial in lammps website. it may help you. wish all you best.
Xuepeng

Dear Xuepeng

Thank you for your comment. In my case I have to generate the geometry of the nanowire by Material studio
and import it to LAMMPS by using “read_data” . In the tutorial "INF INF " is used to set the infinite length conditions
but I still don’t know how to set the same conditions while importing the geometry of the nanowire using “Read_data”
and what BCs to use.

Regards,
Z

I’m not sure why you have to make the structure in Materials Studio, but you may want to reread the link Xuepeng provided. The only portion that lists “INF” are where a region is being defined -> has nothing to do with if the system is periodic. This was being used as one of the commands for creating the nanowire.

As for your original question, the following line is clearly defined in the link he provided and determines the periodicity:
“boundary p p p”

However, keep in mind this page is a tutorial for getting beginners started with LAMMPS. The question of if it will work to simulate your personal research problem is up to you.

Michael

You cannot have an ‘infinite wire’ in LAMMPS due to conceptual issues; it has been discussed many times on this list