Calculus of Variations and Geometric Measure Theory

L. De Luca - A. Ninno - M. Ponsiglione

Vectorial crystallization problems and collective behavior

created by ponsiglio on 08 Aug 2020
modified by deluca on 19 Jan 2022


Published Paper

Inserted: 8 aug 2020
Last Updated: 19 jan 2022

Journal: J. Math. Biol.
Volume: 84
Year: 2022
Doi: 10.1007/s00285-021-01704-0


We propose and analyze a class of vectorial crystallization problems, with applications to crystallization of anisotropic molecules and collective behavior such as birds flocking and fish schooling. We focus on two-dimensional systems of ``oriented'' particles: Admissible configurations are represented by vectorial empirical measures with density in $\mathcal S^1$. We endow such configurations with a graph structure, where the bonds represent the ``convenient'' interactions between particles, and the proposed variational principle consists in maximizing their number. The class of bonds is determined by hard sphere type pairwise potentials, depending both on the distance between the particles and on the angles between the segment joining two particles and their orientations, through threshold criteria.

Different ground states emerge by tuning the angular dependence in the potential, mimicking ducklings swimming in a row formation and predicting as well, for some specific values of the angular parameter, the so-called {\it diamond formation} in fish schooling.

Keywords: Variational methods, crystallization, Collective behavior, Graph theory