Data for: Universal thermal breakdown of polaron coherence in one, two, and three dimensions

Holstein addressed it in 1959 only in the extreme antiadiabatic, strong-coupling limit, while more recent numerically exact approaches are largely restricted to one dimension. Here we solve this problem on square and simple cubic lattices across the weak-, intermediate-, and strong-coupling regimes.

We show that the polaron effective mass $m^*$ and inverse lifetime $1/\tau$ increase monotonically with temperature until, at $T \sim 0.5\,\Omega$, the quasiparticle peak dissolves into a broad incoherent thermal continuum. The phonon frequency $\Omega$ therefore defines a universal coherence scale, independent of dimensionality and coupling strength, validating Holstein's prediction far beyond the regime in which it was derived.