LIGGGHTS® - User Forum

Hi All,
I am a new user.
I implemented the following simulation [in.packing]:
Box with periodic boundaries filled with 9261 particles with size and velocities read from data file I created [data.packing].
I am using a linear spring dashpot contact model. Quantities are scaled in such a way that are dimensionless: M=10-9 kg, L=10-3m, T=10-6s.

I acquire the dump files in Matlab and, for each particle, I compute the overlaps with other particles and the elastic forces (output from LIGGGHTS) acting on it.

Hi everyone,

Hello, I've done a few simulations trying with 1, 4 and 8 processors, and I got higher calculation time for 4, and even more, for 8 processors. In the input script, I tried two thing. First I didn't set any parameter for "Processors", and then I try with several combinations. I noticed that I could get better calculation time chosing aproppiate values in "Processors", but it is not better than a single processor. I read the recomendations in the manual where is explained what to do to get better performance.

I want to calculate residence time distribution of a system. I used the following lines in the script:

region rtd block 0 0 0 0.01 0 0.01 units box
fix rt all property/atom/tracer region_mark rtd mark_step 1000 marker_style dirac check_mark_every 1000
compute nparticles all nparticles/tracer/region region_count rtd tracer rt
fix extra all print 100 $nparticles file rttd.txt

but this error occurs:
ERROR on proc 0: Substitution for illegal variable (input.cpp:410)

Dear LIGGGHTS users,

I have a simple problem related to dump custom command.
I have defined a per-atom vector which has 12 elements. I perform some calculations on this vector and want to dump it out, however I get the following error.

"Dump custom fix ID does not compute per-atom vector"

This is the input script commands I use:

fix LB all property/atom LB vector yes no no -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
dump dmp all custom ${nDump} dump.${OutName} id type f_LB[1] ....f_LB[12]

Dear all,

Happy new year 2015 to all members,

To start a new year, I would like to be clarified concerning a solution to convert dump/local output to VTK file. Looking into several discussions in terms of this issue, I am enable to have EVTK and dump2forcenew.py ( or dump2force.py by Mark Bentley) routine however the running come out with error:

File "...LIGGGHTS/mylpp/src/dump2forcenew.py", line 74, in
if forcedata.snaps[fileindex].natoms !=0 and len(forcedata.snaps[0].atoms[0]) != 11:
IndexError: list index out of range

Is LIGGGHTS enable to model the fracture of particles? such as what happens in a ball mill?

Hi, All:

I was trying to use the dynamic load balancing of LIGGHTS to minimize the computational time. I found the following document: http://cfdem.dcs-computing.com/media/DEM/benchmarks/LIGGGHTS_Benchmarks.pdf, the LIGGGHTS version I am using is: Version LIGGGHTS-PUBLIC 3.0.6

However if I try to use the load balancing command (e.g. in page 43 of the document) :

fix lb all balance 0 xyz 10 1.1 out balance.txt

The program prompts the error:

Hello, can you give me any info about how to use multiprocessing in Liggghts 3.0.6? i mean, usually in 3.0.2 i was using mpirun for 4 my procs and it worked well! and after the installation of the new version, it does not work anymore... is something changed? Thanks for your answers!

Dear all,

I am simulating two spheres (sphere1 and sphere2) which are dropped in rotating cylinder.

I'm looking for a command that give me the total number of interaction that sphere1 participates(total number of interact with wall and with sphere 2) .

I tried the commands (compute wall/gran/local id …..and pair/gran/local id and then dump local), but I got the IDs of particles in contact at each timesteps.However I am looking for the total number of interactions.

Thank you in advance.

Best,

Abdul