Hi all
I want to set some value for “volume fraction” of my simulation.
I know that I can read the volume of simulation cell and also the total number of particles from lammps, but I need to know the total value of atoms for calculating the APF.

1- Can anyone help me to find the volume of atoms?

2- Is there any way to read the volume of each atom, so that with having total “N” , I can find total volume for all of the atoms??

Hi all
I want to set some value for "volume fraction" of my simulation.
I know that I can read the volume of simulation cell and also the total
number of particles from lammps, but I need to know the total value of atoms
for calculating the APF.

1- Can anyone help me to find the volume of atoms?

this is a regularly discussed topic on this mailing list. i suggest
you review previous discussions in the mailing list archives.

2- Is there any way to read the volume of each atom, so that with having
total "N" , I can find total volume for all of the atoms??

unless you are using particles in your simulation with an explicit
volume (atom_style sphere), you are simulating point particles and
those have no volume. thus the best you can do is to define an
"effective volume" for each atom, which is not as straightforward as
you might think, unless you look at the entire system and want to
compute the average over all particles. LAMMPS does provide the
voronoi/atom compute that allows to do a voronoi tesselation, which
uses an specific algorithm to divide the space and assign voxels to
atoms. however, voronoi tesselation is primarily meaningful for 3d
periodic condensed systems. if you have non-periodic boundaries or a
system with surfaces, the size of the voxels at the surface is
dependent on the size of the box, which is arbitrary in those cases.
in those cases, the volume of an atom is ill-defined.