Nonlinear driven response of a phase-field crystal in a periodic pinning potential.
Nonlinear driven response of a phase-field crystal in a periodic pinning potential.
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DOI：
10.1103/physreve.79.011606
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发表时间：
2009-01
期刊：
影响因子：
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通讯作者：
C. Achim;J. P. Ramos;M. Karttunen;K. Elder;E. Granato;T. Ala‐Nissila;S. Ying
中科院分区：
文献类型：
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作者：
C. Achim;J. P. Ramos;M. Karttunen;K. Elder;E. Granato;T. Ala‐Nissila;S. Ying
本文用数值方法研究了最近引入的固定晶格体系相场晶体模型的相图和在驱动作用下的响应。该模型将晶格系统描述为存在周期性钉住势的连续密度场，允许晶格的弹性和塑性变形。我们首先给出了在没有驱动力的情况下模型相图的结果。然后，通过不同失配值和不同钉钉强度的过阻尼运动方程，研究了初始钉钉相称相上驱动力的非线性响应。当钉钉强度较大时，驱动脱屑转变是连续的，滑动速度随力阈值的幂律指数变化，与分析预测一致。在二维中也发现了运动状态下的横向脱屑跃迁。令人惊讶的是，对于足够弱的钉钉势，我们发现在过阻尼动力学下，即使在一维中，也存在具有滞后的不连续钉钉转变。我们还详细描述了接近脱皮过渡的系统结构变化。
We study numerically the phase diagram and the response under a driving force of the phase field crystal model for pinned lattice systems introduced recently for both one- and two-dimensional systems. The model describes the lattice system as a continuous density field in the presence of a periodic pinning potential, allowing for both elastic and plastic deformations of the lattice. We first present results for phase diagrams of the model in the absence of a driving force. The nonlinear response to a driving force on an initially pinned commensurate phase is then studied via overdamped dynamic equations of motion for different values of mismatch and pinning strengths. For large pinning strength the driven depinning transitions are continuous, and the sliding velocity varies with the force from the threshold with power-law exponents in agreement with analytical predictions. Transverse depinning transitions in the moving state are also found in two dimensions. Surprisingly, for sufficiently weak pinning potential we find a discontinuous depinning transition with hysteresis even in one dimension under overdamped dynamics. We also characterize structural changes of the system in some detail close to the depinning transition.