{In a recent paper, Physical Review Letters 87, 167010/1-4 (2001), Moukouri and Jarrell presented evidence that in the two-dimensional (d=2) Hubbard model at half-filling there is a metal-insulator transition (MIT) at finite temperature even in weak coupling. While we agree with the numerical results of that paper, we arrive at different conclusions: The apparent gap at finite-temperature can be understood, at weak-coupling, as a crossover phenomenon involving large (but not infinite) antiferromagnetic (AFM) correlation length. Phase-space effects on the self-energy in d=2 are crucial, as are the ratio between AFM correlation length and single-particle thermal de Broglie wavelength. In weak coupling

10aCondensed matter10aMany-Body10aSimulation1 aKyung, B1 aLandry, J S1 aPoulin, D1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/6227