Seeking a better method of particle looping

Hi all,

I am building a package for non-bonded interactions where are all the interactions via gridded densities and there are no short-range non-bonded interactions. Currently the package calculates interactions between groups, however I would like to move it toward particle types instead since each group is defined as a single particle type, i.e., all groups are defined similar to group A type 1.

Currently, I loop over all particles that are in a processor’s domain, and add the particle’s density to its group’s density grid using groupbits as the check. I want to move away from group based interactions and define these interactions based off particle types. How can one loop over all particles of a certain type? The particle type does not seem to have a similar functionality to groupbits.

Thanks in advance,

What you refer to as group bits I assume means this:
Loop over all particles, check the group mask and skip
particles that don’t match.

For types, isn’t that the same as this:
Loop over all particles, check the type and skip
particles not of the desired type(s).