I have been doing some simulations on srd-big particles mixture. The issue - Fix SRD: too many big particles in bin- came up a few times in the mailing list before where they argued that their system don’t really have this situation.
The units are LJ. My box size is 202020 I have placed about 500 big particles in the box each with diameter 1.0. The number of srd particles is 202020*5. The fix srd command is
fix 1 srd srd 20 big 1.0 1.0 12345 search 1.0
Both the srd and search bin width is 1.0
After running for few hundred steps the simulation terminated with the above mentioned error. In the debugging process 1. I have added this line printf("\n%d \n", nbinbig[jbin]); before error->one(FLERR,“Fix SRD: too many big particles in bin”); to print the number of big particles in any search bin for the initial configuration. Some of the bins have up to 20 big particles per search bin. This don’t seem to be right. The big particles are placed more than 1 unit distance away from each other. So in any given bin there is no possibility of having upto 20 big particles per bin. I have decreases the big particles diameter to as small as 0.01 and the search bin size to 0.2, even then the variable nbinbig[jbin] is showing upto 10 big particles per bin for the initial configuration.
I couldn’t find the code where nbinbig is being calculated. Can you please point me to the line number where nbinbig is being calculated.
- I commented out the line - error->one(FLERR,“Fix SRD: too many big particles in bin”); and rerun the simulation. The simulation ran fine till the end and visualizing the trajectory in VMD also seems to be OK.
I am wondering of a possible bug in the calculation of nbinbig.
Could you please look into it …
Thank you very much.