Error analysis of a linear numerical scheme for the Landau–Lifshitz equation with large damping parameters

Yongyong Cai, Jingrun Chen, Cheng Wang, Changjian Xie*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

A second-order accurate, linear numerical method is analyzed for the Landau–Lifshitz equation with large damping parameters. This equation describes the dynamics of magnetization, with a non-convexity constraint of unit length of the magnetization. The numerical method is based on the second-order backward differentiation formula in time, combined with an implicit treatment for the linear diffusion term from the harmonic mapping part and explicit extrapolation for the nonlinear terms. Afterward, a projection step is applied to normalize the numerical solution at a point-wise level. This numerical scheme has shown extensive advantages in the practical computations for the physical model with large damping parameters, which comes from the fact that only a linear system with constant coefficients (independent of both time and the updated magnetization) needs to be solved at each time step, and has greatly improved the numerical efficiency. Meanwhile, a theoretical analysis for this linear numerical scheme has not been available. In this paper, we provide a rigorous error estimate of the numerical scheme, in the discrete (Formula presented.) norm, under suitable regularity assumptions and reasonable ratio between the time step size and the spatial mesh size. In particular, the projection operation is nonlinear, and a stability estimate for the projection step turns out to be highly challenging. Such a stability estimate is derived in details, which will play an essential role in the convergence analysis for the numerical scheme, if the damping parameter is greater than 3.

Original languageEnglish
Pages (from-to)18952-18974
Number of pages23
JournalMathematical Methods in the Applied Sciences
Volume46
Issue number18
DOIs
Publication statusPublished - Dec 2023
Externally publishedYes

Keywords

  • convergence analysis
  • Landau–Lifshitz equation
  • large damping parameters
  • linear numerical scheme
  • second-order accuracy
  • stability estimate for the projection step

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