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arXiv 0905.4127cond-mat.dis-nn
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d=2和d=3维安德森局域化模型的重整化在位能和重整化跳跃的统计

Statistics of renormalized on-site energies and renormalized hoppings for Anderson localization models in dimensions d=2 and d=3

Cecile Monthus, Thomas Garel

摘要:

对于安德森局域化模型,在固定能量下存在一个精确的实空间重整化过程,它保持了其余位置的格林函数[H. Aoki,J.Phys.C13,3369(1980)]。利用这一过程的安德森紧束缚模型的尺寸$d=2,3$,我们研究了数值的统计性质的重整化在位能量$ε$和重整化跳跃$V$的线性尺寸$L$的函数。我们发现,重整化的现场能量$ε$保持有限的本地化阶段在$d=2,3$和在临界($d=3$),在$ε=0$有限的密度和幂律衰减$1/ε^2$在大$| ε|$。对于定域相中的重整化跳跃,我们发现:${\rm ln} V_L \simeq -\frac{L}{ξ_{loc}}+L^ωu$,其中$ξ_{loc}$是定域长度,$u$是一阶随机变量。指数$ω$是表征定向聚合物在尺寸为$1+(d-1)$的随机介质中的强无序相的液滴指数,其中$ω(d=2)=1/3$和$ω(d=3) \simeq 0.24$。在临界$(d=3)$,重整化跳跃$V$的统计是多重分形,直接对应于个人本征态和两点传输的多重分形。特别是,我们测量$ρ_{typ}\simeq 1$的指数管理的典型衰减$\overline{{\rm ln} V_L} \simeq -ρ_{typ} {\rm ln}L$,与以前的数值措施$α_{typ} =d+ρ_{typ} \simeq 4$的奇异谱$f(α)$的个人特征函数。我们还提出了有关临界表面性质的数值结果。

英文摘要:

For Anderson localization models, there exists an exact real-space renormalization procedure at fixed energy which preserves the Green functions of the remaining sites [H. Aoki, J. Phys. C13, 3369 (1980)]. Using this procedure for the Anderson tight-binding model in dimensions $d=2,3$, we study numerically the statistical properties of the renormalized on-site energies $ε$ and of the renormalized hoppings $V$ as a function of the linear size $L$. We find that the renormalized on-site energies $ε$ remain finite in the localized phase in $d=2,3$ and at criticality ($d=3$), with a finite density at $ε=0$ and a power-law decay $1/ε^2$ at large $| ε|$. For the renormalized hoppings in the localized phase, we find: ${\rm ln} V_L \simeq -\frac{L}{ξ_{loc}}+L^ωu$, where $ξ_{loc}$ is the localization length and $u$ a random variable of order one. The exponent $ω$ is the droplet exponent characterizing the strong disorder phase of the directed polymer in a random medium of dimension $1+(d-1)$, with $ω(d=2)=1/3$ and $ω(d=3) \simeq 0.24$. At criticality $(d=3)$, the statistics of renormalized hoppings $V$ is multifractal, in direct correspondence with the multifractality of individual eigenstates and of two-point transmissions. In particular, we measure $ρ_{typ}\simeq 1$ for the exponent governing the typical decay $\overline{{\rm ln} V_L} \simeq -ρ_{typ} {\rm ln}L$, in agreement with previous numerical measures of $α_{typ} =d+ρ_{typ} \simeq 4$ for the singularity spectrum $f(α)$ of individual eigenfunctions. We also present numerical results concerning critical surface properties.

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