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arXiv 1202.5673cond-mat.stat-mech
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随机完美格与球填充问题

Random perfect lattices and the sphere packing problem

Alexei Andreanov, Antonello Scardicchio

摘要:

出于寻找最佳格球填充在欧氏空间的大尺寸,我们研究随机生成的完美格在中等大尺寸(包括D=19)。完美格与格球填充问题的解决方案有关,因为最好的格填充是完美格,并且因为它们可以通过算法容易地生成。然而,他们的数量增长超指数的维度,所以得到一个想法,他们的属性,我们建议研究一个随机版本的算法,并定义一个随机合奏的方式让人想起一个蒙特卡罗模拟的有效温度。因此,我们研究了这些合奏的包装分数和接吻数的分布,并显示如何作为温度降低,最好的知道包装机很容易恢复。我们发现,即使在无限温度下,典型的完美晶格也比已知的族密度大得多(如A_d和D_d),我们提出了两个假设,我们不能区分在本文中:其中一个是他们改进了Minkowsky的界限phi \sim 2^{-(0.84 ± 0.06)d},和竞争者,其中它们的堆积分数超指数地降低,即φ \sim d^{-a d},但具有非常小的系数a=0.06+-0.04。我们还发现的随机游走的性质是暗示一个玻璃系统已经适度小尺寸。我们还分析了完美格点网络的局部结构,证明了这是一个在所有维度上具有常数标度指数2.6 ± 0.1的无标度网络。

英文摘要:

Motivated by the search for best lattice sphere packings in Euclidean spaces of large dimensions we study randomly generated perfect lattices in moderately large dimensions (up to d=19 included). Perfect lattices are relevant in the solution of the problem of lattice sphere packing, because the best lattice packing is a perfect lattice and because they can be generated easily by an algorithm. Their number however grows super-exponentially with the dimension so to get an idea of their properties we propose to study a randomized version of the algorithm and to define a random ensemble with an effective temperature in a way reminiscent of a Monte-Carlo simulation. We therefore study the distribution of packing fractions and kissing numbers of these ensembles and show how as the temperature is decreased the best know packers are easily recovered. We find that, even at infinite temperature, the typical perfect lattices are considerably denser than known families (like A_d and D_d) and we propose two hypotheses between which we cannot distinguish in this paper: one in which they improve Minkowsky's bound phi\sim 2^{-(0.84+-0.06) d}, and a competitor, in which their packing fraction decreases super-exponentially, namely phi\sim d^{-a d} but with a very small coefficient a=0.06+-0.04. We also find properties of the random walk which are suggestive of a glassy system already for moderately small dimensions. We also analyze local structure of network of perfect lattices conjecturing that this is a scale-free network in all dimensions with constant scaling exponent 2.6+-0.1.

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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