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arXiv cond-mat/0302003cond-mat.stat-mechcond-mat.mtrl-scimath-phmath.MP
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具有可计算稳态的非线性随机方程

Non-Linear Stochastic Equations with Calculable Steady States

Rava A. da Silveira, Mehran Kardar

摘要:

我们考虑广义的Kardar-Parisi-Zhang方程,容纳空间各向异性和耦合演化的几个领域,并专注于它们的对称性和非微扰性质。特别是,我们推导出广义波动耗散条件的形式(非线性)方程的实现高斯概率密度的领域中的稳定状态。对于一维单高度场的非晶生长,我们给出了一类具有可精确计算(高斯和更复杂)稳态的一般方程。在两个维度上,我们表明,任何各向异性系统在长时间和长度尺度上的演变通常的各向同性强耦合制度或与隐藏的对称性相关的线性不动点。类似的结果来自纹理生长方程耦合的高度场与额外的序参量波动的生长表面上。在这种情况下,我们提出了晶体材料的生长,其中的高度场与晶格畸变相互作用的唯象方程,并确定两种特殊情况下,获得高斯稳态。在第一种情况下,压缩模式的影响增长和平流的高度波动,而在第二种情况下,它是位错的密度,耦合的高度。

英文摘要:

We consider generalizations of the Kardar--Parisi--Zhang equation that accomodate spatial anisotropies and the coupled evolution of several fields, and focus on their symmetries and non-perturbative properties. In particular, we derive generalized fluctuation--dissipation conditions on the form of the (non-linear) equations for the realization of a Gaussian probability density of the fields in the steady state. For the amorphous growth of a single height field in one dimension we give a general class of equations with exactly calculable (Gaussian and more complicated) steady states. In two dimensions, we show that any anisotropic system evolves on long time and length scales either to the usual isotropic strong coupling regime or to a linear-like fixed point associated with a hidden symmetry. Similar results are derived for textural growth equations that couple the height field with additional order parameters which fluctuate on the growing surface. In this context, we propose phenomenological equations for the growth of a crystalline material, where the height field interacts with lattice distortions, and identify two special cases that obtain Gaussian steady states. In the first case compression modes influence growth and are advected by height fluctuations, while in the second case it is the density of dislocations that couples with the height.

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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