Convergence of the Planewave Approximations for Quantum Incommensurate Systems

This work studies the spectrum distribution of incommensurate Schrödinger operators. We characterize the density of states for the incommensurate system and develop novel numerical methods to approximate them. In particular, we (i) justify the thermodynamic limit of the density of states in the real space formulation; and (ii) propose efficient numerical schemes to evaluate the density of states based on planewave approximations and reciprocal space sampling. We present both rigorous analysis and numerical simulations to support the reliability and efficiency of our numerical algorithms.