[lammps-users] How can i write the initial configuration for different diameter of segments in LAMMPS? Thanks

Hi, Axel,
Thanks for your email.

please always keep the list in cc, so that people see where
the discussion is going.

At first, I just want to build chain with different diameter for segments.
I consider that all the segments are spherical site-site interaction.

i still don't understand what you want to do.

chains of what? diameter of what?

How can i build such modeling?

what exactly are you looking for? how to input/generate
coordinates, or what parameters to use? or how to define
interactions etc. etc.

please keep in mind that any help can only be as good
as the information and details that you provide.

cheers,
    axel.

Hello, Axel,
Thanks.
Attachment is an example what i did.
In that example, all diameters are the same.
Now, i want to increase the diameter of the first kind of atom.
How can i change the coordinate?
And how can i change parameter in the in2.chain or input ?
Thanks very much
Houyang

in2.chain (512 Bytes)

input (2.08 KB)

parm.chain (230 Bytes)

Hello, Axel,
Thanks.
Attachment is an example what i did.
In that example, all diameters are the same.
Now, i want to increase the diameter of the first kind of atom.

you can answer that by yourself by answering the following question:

which part of a lennard-jones potential relates to the size of
a particle?

please note that in a lennard-jones (or morse or other similar 'soft'
potentials)
there is no 'real' diameter. the relative size of a particle is more
conveniently
defined over the distance where the potential between a pair of sites
is minimal.

How can i change the coordinate?

how about using a text editor? or writing a small program/script that
writes a data file (which you have named 'input')?

And how can i change parameter in the in2.chain or input ?

with a text editor? i don't think that you need to sacrifice a chicken
or bow ten time towards south or do some other voodoo to get
these numbers changed.

i am still confused about what your problem is.
is this the first time you are using MD?

cheers,
    axel.