Achim C V, Ramos J A P, Karttunen M, Elder K R, Granato E, Ala-Nissila T, Ying S C
Department of Applied Physics, Helsinki University of Technology, P.O. Box 1100, FIN-02015 TKK, Espoo, Finland.
Phys Rev E Stat Nonlin Soft Matter Phys. 2009 Jan;79(1 Pt 1):011606. doi: 10.1103/PhysRevE.79.011606. Epub 2009 Jan 26.
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.
我们对最近引入的用于一维和二维系统的钉扎晶格系统的相场晶体模型，在驱动力作用下的相图和响应进行了数值研究。该模型将晶格系统描述为存在周期性钉扎势时的连续密度场，允许晶格发生弹性和塑性变形。我们首先给出该模型在无驱动力情况下的相图结果。然后，通过针对不同失配和钉扎强度值的过阻尼动力学运动方程，研究了初始钉扎的共格相上对驱动力的非线性响应。对于大钉扎强度，驱动去钉扎转变是连续的，并且滑动速度随力从阈值开始以幂律指数变化，这与解析预测一致。在二维中还发现了运动状态下的横向去钉扎转变。令人惊讶的是，对于足够弱的钉扎势，即使在过阻尼动力学下的一维系统中，我们也发现了具有滞后现象的不连续去钉扎转变。我们还详细刻画了系统在接近去钉扎转变时的结构变化。
