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arXiv 1108.6136math.APmath-phmath.MP
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具有长程晶格相互作用的离散NLS的连续极限

On the continuum limit for discrete NLS with long-range lattice interactions

Kay Kirkpatrick, Enno Lenzmann, Gigliola Staffilani

摘要:

考虑网格步长为$h>0$的格点$h \mathbb{Z}$上的一类离散非线性Schroedinger方程(DNLS).在$h \to 0$的连续极限下,我们证明了极限动力学是由$\mathbb{R}$上的一个非线性Schroedinger方程(NLS)给出的,该方程以分数Laplacian $(-Δ)^α$为色散符号.特别地,我们得到分数幂$1/2 < α< 1$在传递到连续极限时由长程晶格相互作用产生,而具有非分数拉普拉斯$-Δ$的NLS描述了短程晶格相互作用的连续极限中的色散(例如,最近邻相互作用)。我们的结果严格证明某些NLS模型方程与分数拉普拉斯在物理文献中提出的。此外,本文所给出的结论也可用于讨论其他长程相互作用晶格系统的连续极限。

英文摘要:

We consider a general class of discrete nonlinear Schroedinger equations (DNLS) on the lattice $h \mathbb{Z}$ with mesh size $h>0$. In the continuum limit when $h \to 0$, we prove that the limiting dynamics are given by a nonlinear Schroedinger equation (NLS) on $\mathbb{R}$ with the fractional Laplacian $(-Δ)^α$ as dispersive symbol. In particular, we obtain that fractional powers $1/2 < α< 1$ arise from long-range lattice interactions when passing to the continuum limit, whereas NLS with the non-fractional Laplacian $-Δ$ describes the dispersion in the continuum limit for short-range lattice interactions (e.g., nearest-neighbor interactions). Our results rigorously justify certain NLS model equations with fractional Laplacians proposed in the physics literature. Moreover, the arguments given in our paper can be also applied to discuss the continuum limit for other lattice systems with long-range interactions.

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