Warning: less insertions than requested <../fix_pour.cpp:676>

Hi there,

I am using Lammps to pack polydisperse spheres. But there is an error: Warning: less insertions than requested <…/fix_pour.cpp:676>. What is the general reason for this error? Which part of script should I revise?

Thanks.

Andrew

Hi there,

I am using Lammps to pack polydisperse spheres. But there is an error:
Warning: less insertions than requested <../fix_pour.cpp:676>. What is the
general reason for this error? Which part of script should I revise?

the error message is pretty much self explanatory: your system is set
up in such a way and your fix pour command uses parameters, so that it
cannot fill up to the expected density due to overlaps. without
knowing your system and details of your simulation, it is difficult to
make suggestions. you know much better what you asked LAMMPS to do.
you just need to keep in mind that in general, it is difficult to fill
up a system to "native" density with (randomized) particle insertion.

axel.

Thank you, Axel. I got it. I am a very beginner of Lammps.

One more question is: how can I arrange the order of atoms' id in output file? Please see a part of dump file below. The atoms' id is not in order. I need the id order like 1, 2, 3, 4, ..., N. Which command should I use in input script? Thanks a lot.

ITEM: ATOMS id type xs ys zs
988 1 0.58364 0.0374868 0.675892
1999 1 0.723755 0.124774 0.677668
2812 1 0.465844 0.357792 0.677421
3618 1 0.45288 0.396213 0.676516
3585 1 0.784444 0.481975 0.676949
3324 1 0.598511 0.4878 0.677626
1146 1 0.248529 0.506728 0.675665

Hi.

The dump command description in LAMMPS documentation (http://lammps.sandia.gov/doc/dump.html) has the following info which will help you:

Unless the dump_modify sort option is invoked, the lines of atom information written to dump files (typically one line per atom) will be in an indeterminate order for each snapshot. This is even true when running on a single processor, if the atom_modify sort option is on, which it is by default. In this case atoms are re-ordered periodically during a simulation, due to spatial sorting. It is also true when running in parallel, because data for a single snapshot is collected from multiple processors, each of which owns a subset of the atoms.

There are also some dump styles (like dump xyz) which will give you sorted output…

Manoj

Hi,

I added following command to input script:

Reorder atoms’id

atom_modify sort 100 0.1

But it seems not working. See the output below:

ITEM: ATOMS id x y z radius
3 0.339146 0.0341088 0.795736 0.0361665
2 0.7838 0.333147 0.89383 0.0935598
1 0.947702 0.0358786 0.970568 0.0875496
5 0.923121 0.887449 0.908308 0.0398416
4 0.238527 0.930263 0.957114 0.0937492

Hi,

I added following command to input script:

# Reorder atoms'id
atom_modify sort 100 0.1

But it seems not working. See the output below:

​oh, it *does* work, but it doesn't do what you are expecting, ​because
this is not what you were recommended to do.
atom_modify sort will change how data is stored *internally* and the
sorting is meant to improve data locality and thus performance and is *not*
according to atom ids. if you look at the documentation, you will see this
explained.

what you were suggested to look at is the *dump_modify* command. that can
perform additional sorting of data before it is output to the dump file.
please note that this incurs additional overhead and communication.

that said, there usually is no need to have sorted dump files for as long
as you store the atom ids, as you can use that information, to store data
while reading into sorted (by atom id) order.

axel.

I got it. Thank you very much.