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

本文提出了一个以Ising体系为核心的限制性固体-固体（RSOS）模型（RSOS-IC）来研究表面与吸附质之间的热力学相互作用。对RSOS-IC模型的邻面进行了统计力学计算。结果1.在吸附物间存在横向吸引作用的情况下，研究了表面自由能、吸附覆盖度、台阶张力和台阶刚度与斜率、温度和化学势的关系。然后，我们建立了平衡态下的热阶聚束（或宏观阶聚），我们称之为热阶聚束。我们发现产生热阶跃聚束的两种机制：外场诱导聚束和吸附 ...更多信息 密度涨落引起的聚束. 2.吸附物之间横向存在排斥作用的情况.在这种情况下，场引起的热阶跃聚束如预期的那样消失了.另一方面，出现了涨落引起的热阶跃聚束。在低温条件下，具有吸附的平面表面具有吸附诱导的有序结构，分子量为<$2x <$2R45。在高温下，有序结构被破坏成1 × 1无序结构。在有序-无序转变温度附近，吸附诱导的有序结构的涨落引起了台阶间的短程吸引相互作用。然后，由于吸附引起的台阶间吸引力，台阶冷凝。3.台阶与吸附之间存在强微观相互作用的情况，台阶刚度与温度的非单调关系的表面模型，目前还不清楚。我们发现，RSOS-IC模型显示出非单调的温度依赖性的台阶和吸附质之间的强微观相互作用的情况下，台阶刚度。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