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arXiv 1005.2201math.NAcs.NAphysics.comp-ph
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多积算子分裂作为求解自治和非自治方程的一般方法

Multi-product operator splitting as a general method of solving autonomous and non-autonomous equations

Texas A&M University(德克萨斯农工大学);Humboldt-Universität zu Berlin(柏林洪堡大学)

Siu A. Chin, Jurgen Geiser

AI总结:

本文提出多积算子分裂方法,通过将时间步进算子分解为指数算子的乘积和,统一构造了偶数和奇数阶龙格-库塔及Nyström积分器,并利用铃木前向时间导数算子处理非自治方程,通过解析外推实现高达100阶的算法,在氢原子基态波函数积分中展示均匀收敛且无极点。

摘要:

在辛积分器近期发展之前,时间步进算子$\e^{h(A+B)}$在研究双曲型偏微分方程时通常被分解为$\e^{h A}$和$\e^{hB}$的乘积和。在求解哈密顿动力学的背景下,我们表明这种分解同时产生了{\it偶数}和{\it奇数}阶的龙格-库塔和Nyström积分器。通过使用铃木的前向时间导数算子来强制时间有序指数,我们表明相同的分解可用于求解非自治方程。特别地,奇数阶算法是基于高度非平凡的{\it时间不对称}核推导的。这种算子方法为理解非结构保持算法提供了通用统一的基础,并且特别适用于通过{\it解析}外推推导非常高阶的算法。在本工作中,通过积分氢原子基态波函数测试了高达100阶的算法。对于这种奇异库仑问题,多积展开显示出均匀收敛,并且没有通常与结构保持方法相关的极点。还讨论了其他例子。

英文摘要:

Prior to the recent development of symplectic integrators, the time-stepping operator $\e^{h(A+B)}$ was routinely decomposed into a sum of products of $\e^{h A}$ and $\e^{hB}$ in the study of hyperbolic partial differential equations. In the context of solving Hamiltonian dynamics, we show that such a decomposition give rises to both {\it even} and {\it odd} order Runge-Kutta and Nyström integrators. By use of Suzuki's forward-time derivative operator to enforce the time-ordered exponential, we show that the same decomposition can be used to solve non-autonomous equations. In particular, odd order algorithms are derived on the basis of a highly non-trivial {\it time-asymmetric} kernel. Such an operator approach provides a general and unified basis for understanding structure non-preserving algorithms and is especially useful in deriving very high-order algorithms via {\it analytical} extrapolations. In this work, algorithms up to the 100th order are tested by integrating the ground state wave function of the hydrogen atom. For such a singular Coulomb problem, the multi-product expansion showed uniform convergence and is free of poles usually associated with structure-preserving methods. Other examples are also discussed.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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