二维非层状材料具有异于传统二维层状材料的特性，其中的二维非层状钙钛矿薄膜由于结构灵活、潜在性质丰富被认为是实现材料功能创新的重要平台。但现有的工作多集中在样品制备方法的改进与本征性质的研究上，鲜有涉及体系新性能的开发。根据前期对二维SrTiO3的研究，申请人推测将二维(001)PbTiO3薄膜进行结构改造后，可在体系局部也可在整体上诱发出新的物理性质。这些新性质还有可能与体系自身的铁电性产生耦合，从而同时实现材料的多功能化与性能的调控。为了证实以上想法，本项目计划基于第一性原理计算研究通过表面修饰与薄膜复合的方式在二维PbTiO3中引入新的物理性质；然后，研究极化强度与极化方向的改变对新物性的影响；最后，研究体系性能随掺杂浓度、应力与薄膜厚度的变化规律，以找到优化体系性能的方法。本项目的成功实施可增加二维PbTiO3薄膜的应用潜力，也可为其他二维钙钛矿材料新性能的开发提供理论参考。

The 2D non-layered materials have properties different from traditional 2D layered materials. Especially, because of its structural diversity and rich physical properties, 2D non-layered perovskite films have become the research hotspot in this field. However, up to now most studies on 2D non-layered perovskite have focused on the improvement of the method of the sample preparation and the study of intrinsic nature, rare reports have seen on development of new properties. Based on our previous works on two-dimensional SrTiO3 film, the applicant speculate that new physical properties can be induced in two-dimensional (001) PbTiO3 film through appropriate modification of the atomic structures, and these new properties may be coupled with the ferroelectric property of the system itself, which is expected to realize the multi-functionalization and property regulation of materials at the same time. In this project, we are going to carry out first-principles calculations to verify the above hypotheses. Our concrete research plans are (i) to introduce new physical properties in two-dimensional PbTiO3 films by surface modification and construction of heterogeneous interfaces; (ii) study if the polarization intensity and polarization direction can be used to regulate these new physical properties; (iii) study the variation of the system properties with deformation, stress, film thickness, etc., and try to find the ways to optimize the system properties. The successful implementation of this project may increase the application potential of two-dimensional PbTiO3 films, and may also provide the theory instruction for the development of new properties of other 2D perovskite films.