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arXiv 0906.3155nlin.SIcs.NAmath-phmath.MPmath.NA
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构建可积格点系统时间离散化的一种系统方法:局部运动方程

A systematic method for constructing time discretizations of integrable lattice systems: local equations of motion

Okayama Institute for Quantum Physics(冈山量子物理研究所)

Takayuki Tsuchida

AI总结:

提出一种基于零曲率表示和最低阶守恒律的方法,用于可积格点系统的时间离散化,保持运动方程的局部性,并确保离散系统具有与连续系统相同的守恒量和解结构。

摘要:

我们提出了一种新方法,用于在保持运动方程局部性的同时,对可积格点系统中的时间变量进行离散化。该方法基于零曲率(Lax对)表示和最低阶“守恒律”。与Ablowitz和Ladik的开创性工作相比,我们的方法允许时间离散化阶段出现的辅助依赖变量用原始依赖变量局部表示。时间离散化的格点系统具有与连续时间格点系统相同的守恒量集合和解结构;只有解中对应于角度变量的参数的时间演化被离散化。通过Toda格点、Volterra格点、修正Volterra格点、Ablowitz-Ladik格点(一个可积半离散非线性薛定谔系统)以及格点海森堡铁磁模型等例子,说明了我们方法的有效性。对于Volterra格点和修正Volterra格点,我们还给出了它们的超离散类似物。

英文摘要:

We propose a new method for discretizing the time variable in integrable lattice systems while maintaining the locality of the equations of motion. The method is based on the zero-curvature (Lax pair) representation and the lowest-order "conservation laws". In contrast to the pioneering work of Ablowitz and Ladik, our method allows the auxiliary dependent variables appearing in the stage of time discretization to be expressed locally in terms of the original dependent variables. The time-discretized lattice systems have the same set of conserved quantities and the same structures of the solutions as the continuous-time lattice systems; only the time evolution of the parameters in the solutions that correspond to the angle variables is discretized. The effectiveness of our method is illustrated using examples such as the Toda lattice, the Volterra lattice, the modified Volterra lattice, the Ablowitz-Ladik lattice (an integrable semi-discrete nonlinear Schroedinger system), and the lattice Heisenberg ferromagnet model. For the Volterra lattice and modified Volterra lattice, we also present their ultradiscrete analogues.

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