bug in fix_atom_swap and suggestion

Hi Steve and colleagues,

I just came into a bug with fix-atom-swap. When you write the restart file from fix-atom-swap,
only one random number generator state is written, while you ask for two when read it. Could
you have this fixed? Thanks.

Also, I would like to suggest you to enable a compute that computes the chemical composition
of the system, i.e., percentage for each atomic type; this generally is not necessary, but with
semi-grand simulations, the composition will change and there is no straightforward way to output
this yet.


LT Kong

I’ll fix it. Thanks.


An equal-style variable can calculate
the percentage of any group, e.g.

variable foo equal count(group)/atoms

A group could be one or more atom types.


Or if you use the new compute chunk/atom
with the chunk defined by atom type,
you can use compute property/chunk or
fix ave/chunk to compute
the count of each chunk. For fix ave/chunk
If you define
an atom-style variable which is just 1/atoms
and norm none, I think you will get percentage
as an output, along with the count. Those
values can be written to a file or time-averaged.