### Why people choose 0.2 as the value of linking length in the friends-of-friends algorithm?

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**January 26 2021**Friends-of-friends (hereafter FOF) algorithm is commonly used to find halos in cosmological simulations. And FOF depends on only one parameter, i.e. linking length, [math], where [math] is the volume of the simulation box, and [math] is the number of dark matter particles.

In most literatures, the value of [math] is set as 0.2. What does [math] means physically?

In most literatures, the value of [math] is set as 0.2. What does [math] means physically?