Unknown reason for 'Masses are not set'

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1

Dear Lammps Users,

I got an error messages ‘All masses are not set’, and after checking the input file as well as the read_data file, I couldn’t identify why this error had occurred. I have paid attention to use ‘set mass’ command instead of ‘Mass’, as ellipsoid style needs a per-particle based mass command. I have attached the read_data file as well as the screen output here.

From the output information, it seems to me that in the beginning the mass has already been assigned to different groups. And that’s what confused me that in the end the system failed from ‘All masses are not set’.

I have tested system where the solvent is water, and it worked very well. And the system right now has polymer melt as the medium, where atom style, bond style and bond topology has been added to the input file as well as read_data file comparing to the system which has water as the medium. All the rest is the same. So far I couldn’t figured out how to avoid this error message in my system, and I am writing to ask if anyone can help me identify where the error came from.

Thanks very much in advance for your help!
Sincerely,
LQ

read_data (69.2 KB)

output (1.64 KB)

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It's a bit confusing, but you are using atom_style hybrid where
bond requires per-type masses and ellipsoid requires per-atom masses.
So you have to define both. From the mass command doc page:

If you define a hybrid atom style which includes one (or more)
sub-styles which require per-type mass and one (or more) sub-styles
which require per-atom mass, then you must define both. However, in
this case the per-type mass will be ignored; only the per-atom mass
will be used by LAMMPS.

Steve