// valid at the neighbor.
// However, we want the particle to keep its position at the local node.
// Thus, we need a copy of the particle.
Particle copy = particle.copy();
copy.addX(-xoffset);
copy.addPrevX(-xoffset);
copy.addY(-yoffset);
copy.addPrevY(-yoffset);
sharedData.registerBorderParticle(copy);
}