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arXiv 2307.03216cond-mat.stat-mech
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运动性如何影响伊辛转变

How motility affects Ising transitions

Chandraniva Guha Ray, Indranil Mukherjee, P. K. Mohanty

AI总结:

研究二维吸引性游走-翻滚粒子模型的相分离转变,发现运动性增加需更强吸引力才能实现伊辛类相变,且运动性阻碍团簇形成。

摘要:

我们研究了一个在方格上的硬核粒子晶格气体模型,粒子间存在最近邻吸引力$J$。每个粒子具有一个独立于其他粒子的内部取向,指向四个最近邻方向之一,并且如果目标格点为空,它可以以通常的Metropolis速率沿该方向移动到相邻格点。粒子的内部取向也可以以恒定速率$\omega$变为其他三个方向中的任意一个。在$\omega \to \infty$的极限下,该模型的动力学退化为晶格气体(LG)的动力学,后者在粒子密度$\rho=\frac12$和温度$T=1$时,当吸引力强度$J$超过阈值$\ln(1+ \sqrt{2})$时表现出相分离转变。该转变属于伊辛普适类。对于任何有限的$\omega>0$,粒子可以被视为二维中具有运动性$\omega^{-1}$的吸引性游走-翻滚粒子(RTPs)。我们发现RTPs也表现出相分离转变,但所需的临界相互作用为$J_c(\omega)$,它随着运动性$\omega^{-1}$的增加而单调增加。该转变似乎属于伊辛普适类。令人惊讶的是,在这些模型中,运动性阻碍了团簇形成过程,需要更强的相互作用来稳定微观团簇。此外,当$J=0$时,未发现类似MIPS的相。

英文摘要:

We study a lattice gas model of hard-core particles on a square lattice experiencing nearest neighbour attraction $J$. Each particle has an internal orientation, independent of the others, that point towards one of the four nearest neighbour and it can move to the neighbouring site along that direction with the usual Metropolis rate if the target site is vacant. The internal orientation of the particle can also change to any of the other three with a constant rate $ω.$ The dynamics of the model in $ω\to \infty$ reduces to that of the Lattice Gas (LG) which exhibits a phase separation transition at particle density $ρ=\frac12$ and temperature $T=1,$ when the strength of attraction $J$ crosses a threshold value $\ln(1+ \sqrt{2}).$ This transition belongs to Ising universality class. For any finite $ω>0,$ the particles can be considered as attractive run-and-tumble particles (RTPs) in two dimensions with motility $ω^{-1}.$ We find that RTPs also exhibit a phase separation transition, but the critical interaction required is $J_c(ω)$ which increases monotonically with increased motility $ω^{-1}.$ It appears that the transition belongs to Ising universality class. Surprisingly, in these models, motility impedes cluster formation process necessitating higher interaction to stabilize microscopic clusters. Moreover, MIPS like phases are not found when $J=0.$

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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