Adaptive multigrid method for quantum eigenvalue problems

In this paper, a new type of adaptive finite element method is proposed for nonlinear eigenvalue problems in electronic structure calculations based on the multilevel correction method and adaptive multigrid method. Different from the classical adaptive finite element method for electronic structure calculations which needs to solve a nonlinear eigenvalue model directly in each adaptive finite element space, our approach only needs to solve a linear elliptic boundary value problem by adaptive multigrid method in each adaptive space, and then correct the eigenpair approximation by solving a smallscale nonlinear eigenvalue model in a low-dimensional correction space. Since solving large-scale nonlinear eigenvalue model is avoided which has exponentially increased computational time, the efficiency of electronic structure calculations can be improved evidently. In addition, the corresponding convergence analysis of the proposed adaptive multigrid algorithm are also derived theoretically and numerically. & COPY; 2023 Elsevier B.V. All rights reserved.