AAPPP

AAPPP is an open source python package written in C that can be used to simulate the 2-d Vicsek model and many more 2-d models of aligning active particles.

You can find it at https://github.com/kuersten/aappp/.

Installation

Before installation you need python3 and pip. Installation should work on Linux and Mac as follows

	bash install.bash

Simulations

You can run simulations from within python3. To initialize a simulation just type

	import aappp
	mysim=aappp.aappp_init(Lx=100, Ly=100, v=1, R=1, eta=0.3, N=10000, seed=1)

Now you are ready to perform some Vicsek time steps

	aappp.VM_update_timesteps(mysim, 10000)

You can save the final simulation state for later use and free memory

	aappp.aappp_save(mysim, 'mydata.dat')
	aappp.aappp_free(mysim)

You can analyze or plot the simulation results yourself, however, an easy way to plot a snapshot is just using the example script 'aappp_snapshot.py'

In terminal you can just type

	python3 aappp_snapshot.py -f mydata.dat -w

Each point corresponds to the position of a particle. The color encodes the direction of motion.

More Info, Measurements, other Models, etc.

The package can measure certain order parameters on the fly, other models are implemented as well, such as e.g. metric free models, nematic interactions, overdamped langevin dynamics and several particle species.

For more info you can confere the documentation from within python via

	import aappp
	help(aappp)

You can also find more info on the package at https://doi.org/10.48550/arXiv.2211.15630.