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

为了研究表面和吸附物之间的热力学相互作用，我们提出了一个与Ising(RSOS-IC)体系耦合的限制固体(RSOS)模型。我们对RSOS-IC模型的邻近表面进行了统计力学计算。利用密度矩阵重整化群(DMRG)算法的扩展方法--乘积波函数重整化群(PWFRG)算法，采用传递矩阵法研究了侧向吸附分子间相互吸引相互作用的情况下，表面自由能、吸附覆盖度、阶跃张力和阶跃刚度与斜率、温度和化学势的关系。然后，我们在平衡中建立了热阶跃聚束(或宏观阶跃形成)，其中我们称之为热力学阶跃凝聚。我们发现引起热阶跃聚束的两种机制：外场诱导聚束和吸附…更多的密度起伏导致聚束。2.横向上吸附物质之间的排斥相互作用。在这种情况下，场诱导的热阶跃聚束如预期的那样消失。另一方面，出现了涨落引起的热阶跃聚束。低温下，吸附平面具有√2x√2R45吸附诱导有序结构。在高温下，有序结构被破坏为杂乱的结构。在有序-无序转变温度附近，吸附诱导的有序结构的涨落导致了台阶之间的短程吸引相互作用。然后，由于吸附诱导的台阶间吸引，台阶凝聚。通过详细的计算，我们得到了相图。3.步骤与吸附之间的强微观相互作用的情况。具有非单调温度依赖关系的表面模型，到目前为止还是未知的。我们发现，当步骤与吸附分子之间存在较强的微观相互作用时，RSOS-IC模型表现出非单调的温度依赖性。较少

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