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arXiv 0705.3135cond-mat.softcond-mat.stat-mech
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准一维条带中固体的反常结构和力学性质

Anomalous structural and mechanical properties of solids confined in quasi one dimensional strips

Debasish Chaudhuri, Surajit Sengupta

摘要:

我们表明,使用计算机模拟和平均场论,一个质点系在两个维度,当横向限制在一个准一维通道内的一对平行的硬壁,具有几个异常的结构和力学性能没有观察到的散装。根据密度$ρ$和壁之间的距离$L_y$,该系统显示类似于弱调制液体,强调制近晶,三角形固体或屈曲相的结构特征。在固定的$ρ$下,$L_y$的变化导致许多凹入的不连续过渡,包括平行于限制壁的层数的变化,这主要取决于层间间距与$L_y$的可互换性。该固体显示出抗拉伸性,但不显示出抗剪切性。当应变超过弹性限度时,它发生塑性形变而失效,但令人惊讶的是,当应变反向时,材料完全恢复并返回到其原始未变形状态。我们从平均场论和有限尺寸模拟得到了相图,并讨论了涨落的影响。

英文摘要:

We show using computer simulations and mean field theory that a system of particles in two dimensions, when confined laterally by a pair of parallel hard walls within a quasi one dimensional channel, possesses several anomalous structural and mechanical properties not observed in the bulk. Depending on the density $ρ$ and the distance between the walls $L_y$, the system shows structural characteristics analogous to a weakly modulated liquid, a strongly modulated smectic, a triangular solid or a buckled phase. At fixed $ρ$, a change in $L_y$ leads to many reentrant discontinuous transitions involving changes in the number of layers parallel to the confining walls depending crucially on the commensurability of inter-layer spacing with $L_y$. The solid shows resistance to elongation but not to shear. When strained beyond the elastic limit it fails undergoing plastic deformation but surprisingly, as the strain is reversed, the material recovers completely and returns to its original undeformed state. We obtain the phase diagram from mean field theory and finite size simulations and discuss the effect of fluctuations.

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