The study of heavy quarkonium suppression in heavy-ion collisions represents an important source
of information about the properties of the quark-gluon plasma produced in such collisions. The
evolution of the reduced density matrix of heavy quarks inside a quark-gluon plasma is described by
a master equation. In a previous work, we found that this master equation needs to take into account
the finite energy gap between singlet and octet states in order to lead to the correct thermalization
at late times. In this talk, we will discuss the phenomenological consequences of taking into account
such energy gap when computing the nuclear modification factor. We will do this in two different
scenarios, one using Hard Thermal Loop perturbation theory and another inspired by recent lattice
QCD results on the static potential.