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1.
自对耦无序分布随机链Potts模型的临界普适性研究   总被引:2,自引:0,他引:2       下载免费PDF全文
以蒙特卡罗模拟方法对自对耦分布二维随机链q态Potts模型的短时临界行为进行了数值研究.利用初始非平衡演化阶段存在的普适幂指数和有限体积标度行为,数值模拟了在不同形式随机分布时q=3和q=8态Potts模型磁临界指数η和动力学临界指数z.计算结果发现η不依赖于自对偶无序分布的具体形式, 从而以数值方法给出了一个关于淬火掺杂自旋系统的临界普适行为的验证. 关键词: 随机链Potts模型 动力学蒙特卡罗模拟 临界普适性  相似文献   

2.
陈建珍  朱建阳 《物理学报》2001,50(7):1340-1345
在单自旋跃迁临界动力学的基础上,利用动力学decimation重整化群技术,在考虑类磁型微扰的情况下,对动力学Gaussian自旋模型在具有扩展对称性的Sierpinski铺垫上的临界慢化行为进行了研究.结果表明,系统的动力学临界指数z仅与静态关联长度临界指数ν有关,而与分形维数Df无关.  相似文献   

3.
陈建珍  朱建阳 《物理学报》2001,50(7):1340-1345
在单自旋跃迁临界动力学的基础上,利用动力学decimation重整化群技术,在考虑类磁型微扰的情况下,对动力学Gaussian自旋模型在具有扩展对称性的Sierpinski铺垫上的临界慢化行为进行了研究.结果表明,系统的动力学临界指数z仅与静态关联长度临界指数ν有关,而与分形维数Df无关.  相似文献   

4.
宋岩  丁鄂江  黄祖洽 《物理学报》1992,41(10):1647-1651
本文研究了二元Sullivan流体在二相共存、三相共存时的临界指数。发现所得临界指数并不依赖于模型参量和动力学势的对称性,具有普适性,同时,这一组临界指数满足标度律。  相似文献   

5.
尹训昌  尹慧  孔祥木 《物理学报》2006,55(9):4901-4905
应用实空间重整化群和累积展开的方法,研究了外场中特殊钻石型等级晶格上S4模型的相变和临界性质,求出了系统的临界点和临界指数. 结果表明,此系统除了存在一个Gauss不动点外,还存在一个Wilson-Fisher不动点,与该等级晶格上的Gauss模型相比较,系统的临界指数发生了变化. 关键词: 钻石型等级晶格 4模型')" href="#">S4模型 重整化群 临界性质  相似文献   

6.
雷晓蔚  郑波  应和平 《物理学报》2007,56(3):1713-1718
应用动力学蒙特卡罗模拟方法,对二维Ising模型和二维XY模型的aging现象展开数值研究.系统在零外场条件下从高温无序相淬火到临界温度Tc时,通过测量自关联函数A(t,t′),观察到二维Ising模型和二维XY模型的aging现象,获得更精确的动力学临界指数λcz的值.特别是对二维XY模型,当初始态为完全无序态时,模拟结果证实存在关于标度行为的对数修正. 关键词: 蒙特卡罗模拟 相变和临界行为 aging现象  相似文献   

7.
丝阵负载Z箍缩内爆动力学研究   总被引:1,自引:0,他引:1       下载免费PDF全文
丝阵负载内爆动力学行为基本可以分为以下四个过程:1)丝的烧蚀;2)壳层的形成;3)内爆;4)滞止.利用所研制的可见光分幅相机和X射线分幅相机在"强光一号"加速器上对多种型号的丝阵负载Z箍缩内爆动力学行为进行了实验研究,获得了从早期单丝烧蚀到等离子体柱崩毁全过程图像,并对实验结果进行了分析,主要研究成果如下:1)发现存在较长时间的丝烧蚀过程,且单丝烧蚀在轴向上并不均匀;实验得到的内爆轨迹与唯像模型计算结果较为一致.2)不论早期的可见光图像还是中后期的软X射线图像都存在明显的阴极发射,内爆后期在阴极附近存在明 关键词: 丝阵 内爆动力学 Z箍缩 脉冲功率技术  相似文献   

8.
特殊钻石型等级晶格上S4模型的临界性质   总被引:5,自引:0,他引:5       下载免费PDF全文
应用实空间重整化群和累积展开的方法,研究了外场中特殊钻石型等级晶格上S4模型的相变和临界性质,求出了系统的临界点和临界指数. 结果表明,此系统除了存在一个Gauss不动点外,还存在一个Wilson-Fisher不动点,与该等级晶格上的Gauss模型相比较,系统的临界指数发生了变化.  相似文献   

9.
三维随机点阵Ising模型的集团Monte Carlo方法模拟   总被引:1,自引:0,他引:1       下载免费PDF全文
季达人  张剑波 《物理学报》1993,42(11):1741-1746
为了解决Monte Carlo模拟中的临界慢化问题,应用S-W方法,对一维随机点阵的模型进行了研究。找到该系统的相变点为βc=0.075±0.001,与此同时,在相变点附近研究了SW方法的动力学性质,计算得动力学临界指数z=0.74±0.03,结果表明,SW方法对克服三维随机点阵Ising模型的临界慢化是非常有效的。 关键词:  相似文献   

10.
Sierpinski镂垫上具有三体自旋作用的Gauss模型   总被引:3,自引:0,他引:3       下载免费PDF全文
刘杰  孔祥木  李永平  黄家寅 《物理学报》2004,53(7):2275-2280
应用实空间重整化群变换和累积展开相结合的方法,在Sierpinski镂垫上研究了二体自旋作用和三体自旋作用都存在时Gauss模型的相变和临界性质,求出了临界点和临界指数.与只有二体自旋作用的情况相比较,在无外场和有外场的情况下,临界点和临界指数都发生了变化,这表明三体自旋作用对其临界点和临界性质都有一定的影响. 关键词: Sierpinski镂垫 Gauss模型 重整化群 临界性质  相似文献   

11.
12.
E. Arashiro  H.A. Fernandes 《Physica A》2009,388(20):4379-4386
We investigate the short-time critical dynamics of the Baxter-Wu (BW) and n=3 Turban (3TU) models to estimate their global persistence exponent θg. We conclude that this new dynamical exponent can be useful in detecting differences between the critical behavior of these models which are very difficult to obtain in usual simulations. In addition, we estimate again the dynamical exponents of the four-state Potts (FSP) model in order to compare them with results previously obtained for the BW and 3TU models and to decide between two sets of estimates presented in the current literature. We also revisit the short-time dynamics of the 3TU model in order to check if, as already found for the FSP model, the anomalous dimension of the initial magnetization x0 could be equal to zero.  相似文献   

13.
Using Monte Carlo methods, the short-time dynamic scaling behaviour of two-dimensional critical XY systems is investigated. Our results for the XY model show that there exists universal scaling behaviour already in the short-time regime, but the values of the dynamic exponent z differ for different initial conditions. For the fully frustrated XY model, power law scaling behaviour is also observed in the short-time regime. However, a violation of the standard scaling relation between the exponents is detected.  相似文献   

14.
We present our Monte Carlo results of the random-bond Potts ferromagnet with the Olson-Young self-dual distribution of quenched disorders in two dimensions. By exploring the short-time scaling dynamics, we find the universal power-law critical behavior of the magnetization and Binder cumulant at the critical point, and thus obtain estimates of the dynamic exponent z and magnetic exponent η, as well as the exponent θ. Our special attention is paid to the dynamic process for the q = 8 Potts model.  相似文献   

15.
16.
The one-dimensional Domany-Kinzel cellular automaton is investigated by two numerical approaches: (i) the spontaneous-search method, which is a method appropriated for a search of criticality; (ii) short-time dynamics. Both critical frontiers of the system are investigated, namely, the one separating the frozen and active phases, as well as the critical line determined by damage spreading between two cellular automata, that splits the active phase into the nonchaotic and chaotic phases. The efficiency of the spontaneous-search method is established herein through a precise estimate of both critical frontiers, and in addition to that, it is shown that this method may also be used in the determination of the critical exponent ν. Using the critical frontiers obtained, other exponents are estimated through short-time dynamics. It is verified that the critical exponents of both critical frontiers fall in the universality class of directed percolation.  相似文献   

17.
The critical relaxation from the low-temperature ordered state of the three-dimensional Ising model with competing interactions on a simple cubic lattice has been studied for the first time using the short-time dynamics method. Competition between exchange interactions is due to the ferromagnetic interaction between the nearest neighbors and the antiferromagnetic interaction between the next nearest neighbors. Particles containing 262144 spins with periodic boundary conditions have been studied. Calculations have been performed by the standard Metropolis Monte Carlo algorithm. The static critical exponents of the magnetization and correlation radius have been calculated. The dynamic critical exponent of the model under study has been calculated for the first time.  相似文献   

18.
It is shown that in the case of human heart rate, the scaling behavior of the correlation sum (calculated by the Grassberger-Procaccia algorithm) is a result of the interplay of various factors: finite resolution of the apparatus (finite-size effects), a wide dynamic range of mean heart rate, the amplitude of short-time variability being a decreasing function of the mean heart rate. This is done via constructing a simple model of heart rhythm: a signal with functionally modulated Gaussian noise. This model reproduces the scaling behavior of the correlation sum of real medical data. The value of the scaling exponent depends on all the above-mentioned factors, and is a certain measure of short-time variability of the signal.  相似文献   

19.
Critical relaxation from a low-temperature fully ordered state of Fe2/V13 iron-vanadium magnetic superlattice models has been studied using the method of short-time dynamics. Systems with three variants of the ratio R of inter-to intralayer exchange coupling have been considered. Particles with N = 262144 spins have been simulated with periodic boundary conditions. Calculations have been performed using the standard Metropolis algorithm of the Monte Carlo method. The static critical exponents of magnetization and correlation radius, as well as the dynamic critical exponent, have been calculated for three R values. It is established that a small decrease in the exchange ratio (from R = 1.0 to 0.8) does not significantly influence the character of the short-time dynamics in the models studied. A further significant decrease in this ratio (to R = 0.01), for which a transition from three-dimensional to quasi-two-dimensional magnetism is possible, leads to significant changes in the dynamic behavior of iron-vanadium magnetic superlattice models.  相似文献   

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