Statistical mechanics of vicinal surface : Thermodynamical interplay between adsorption and surface steps

邻接表面的统计力学：吸附和表面台阶之间的热力学相互作用

基本信息

批准号：
15540323
负责人：
AKUTSU Noriko
金额：
$ 0.96万
依托单位：
Osaka Electro-Communication University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15540323/
关键词：
step bunching adsorption statistical thermodynamics of surfaces and interfaces density matrix renormalization group formation of macro steps first-order transition at the facet edge order-disorder phase transition surface tension of crystal

项目摘要

We have presented a restricted-solid-on-solid (RSOS) model ceupled with Ising (RSOS-IC) system in order to study thermodynamical interplay between surface and adsorbate. We have made statistical mechanical calculation on the vicinal surfacu of the RSOS-IC model. by a transfer matrix method with the product wave-function renormalization group (PWFRG) algorithm, which is an extended method of the density matrix renormalization group(DMRG) algorithm.Results1.The case of the attractive interaction among adsorbates in the lateral direction.We have studied the slope, temperature, and chemical potential dependence of the surface free energy, adsorption coverage, step tension, and step stiffness. Then, we have established the thermal step bunching (or the macro step formation) in the equilibrium, where the thermal step bunching we call is the thermodynamical step condensation. We find that two mechanisms cause the thermal step bunching : the external field induced bunching, and the adsorption … More density fluctuation induced bunching.2.The case of the repulsive interaction among adsorbates in the lateral direction.In this case, the field induced thermal step bunching disappears as is expected. On the other hand, the fluctuation induced thermal step bunching appears. In low temperature, the planar surface with adsorption has adsorption induced ordered structure with √2x√2R45. In high temperature, the order is destroyed to lxldisrodered structure. Around the order-disorder transition temperature, the fluctuation of the adsorption induced ordered structure causes short-range attractive interaction between steps. Then, steps condense due to the adsorption induced inter-step attraction. By the detailed calculation, we have obtained the phase diagram.3.The case of the strong microscopic interaction between step and adsorption.The surface model with the non-monotonic temperature dependence of step stiffness has not known, so far. We find that the RSOS-IC model shown the non-monotonic temperature dependence of the step stiffness in case of the strong microscopic interaction between a step and adsorbates. Less

我们提出了与 Ising (RSOS-IC) 系统耦合的限制固体对固体 (RSOS) 模型，以研究表面和吸附质之间的热力学相互作用。我们对 RSOS-IC 的邻面表面进行了统计力学计算。模型采用乘积波函数重整群（PWFRG）算法的传递矩阵法，该算法是密度矩阵重整群（DMRG）的扩展方法。算法结果1.吸附物之间横向吸引相互作用的情况。我们研究了表面自由能、吸附覆盖度、阶梯张力和阶梯刚度的斜率、温度和化学势依赖性。平衡状态下的热阶聚束（或宏观阶跃形成），我们将热阶聚束称为热力学阶跃凝聚，我们发现引起热阶聚束的机制有两种：外场引起的聚束和吸附。 …更多密度波动引起的聚束。2.吸附物之间横向排斥相互作用的情况。在这种情况下，场引起的热阶聚束如预期消失，另一方面，波动引起的热阶聚束出现。在低温下，具有吸附作用的平面具有吸附诱导的有序结构，其结构为√2x√2R45；在高温下，有序-无序转变温度附近，吸附发生波动。诱导的有序结构引起台阶之间的短程吸引力相互作用，然后，由于吸附诱导的台阶间吸引力，台阶发生凝聚。3.台阶和台阶之间强微观相互作用的情况。阶跃刚度的非单调温度依赖性的表面模型尚不清楚，到目前为止，我们发现RSOS-IC模型在a之间存在强微观相互作用的情况下表现出阶跃刚度的非单调温度依赖性。步骤和吸附物较少