Sharp decay thresholds for eigenvalues of discrete Schr\"odinger operators on $\mathbb{Z}^2$
We study eigenvalues of discrete Schr\"odinger operators $H=\Delta+V$ on $\mathbb{Z}^2$, where $\Delta$ is the uncentered Laplacian, i.e., the un-normalized adjacency operator of $\mathbb{Z}^2$ and $V$ decays at infinity. By Weyl's theorem, the essential spectrum of $H$ is $[-4,4]$. We determine the sharp decay thresho...