Molecular static methods for the simulation of ferroelectric materials

用于模拟铁电材料的分子静态方法

• 批准号: 201207895
• 负责人: Professor Dr.-Ing. Paul Steinmann
• 金额: --
• 依托单位: Lehrstuhl für Technische Mechanik (LTM)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/201207895?language=en
• 关键词: Molecular; static; methods; simulation; ferroelectric

Ferroelectric materials are modelled and simulated on different length scales between the electron structure and the continuum description. Therefore, also atomistic models and algorithms have been developed further in the last decade and attain accurate results.Nevertheless the computational costs of the established atomistic methods are still significant. For that reason atomistic scale simulation methods are further developed.The goal of this project is the development and investigation of molecular static methods for the analysis of electromechanical phenomena on the micro level in ferroelectric materials. Therefore an accurate description of the material on an atomistic scale has to be made to investigate relevant regions, such as domain walls and nanofilms. In order to simulate ferroelectric materials on the micro scale, ab initio methods and molecular dynamics have been used for some time. Yet, not only the small length scale is a limiting factor but also the time step length. Through the use of molecular static methods the dynamic problem shall be transferred to a quasi-static algorithm.In order to simulate ferroelectric materials, the core-shell model is widely used in atomistic simulations. Thereby interactions between atom cores and electron shells are considered by interaction potentials, e.g. the Coulomb potential or the Lennard-Jones potential. The newly developed algorithm has been already used to investigate ferroelectric phenomena, such as domain walls, at the atomistic level. Moreover a new method has been implemented in order to consider macroscopic continuum stresses. Therefore the developed algorithm was able to compute not only the dielectric hysteresis but also the butterfly hysteresis of a ferroelectric crystal.Most molecular static algorithm do not consider temperature. However, in order to simulate phase transitions temperature has to be considered. Therefore a temperature dependent interaction potential has to be included to extend the core-shell model in order to simulate technically relevant structures and phase transitions.In addition to the targeted methodological outcome, the results shall be compared directly to the other projects which use non-atomistic methods for the simulation of ferroelectric materials.

在电子结构和连续描述之间的不同长度尺度上对铁电材料进行建模和模拟。因此，在过去的十年中，还进一步开发了原子模型和算法，并取得了准确的结果。尽管如此，已建立的原子方法的计算成本仍然很重要。因此，进一步开发了原子量表模拟方法。该项目的目的是开发和研究分子静态方法，用于分析铁电材料中微型机械现象的分析。因此，必须在原子量表上对材料进行准确的描述，以研究相关区域，例如域壁和纳米膜。为了模拟微型尺度的铁电材料，从头开始方法和分子动力学已有一段时间了。但是，不仅长度尺度是一个限制因素，而且是时间步长。通过使用分子静态方法，应将动态问题转移到准静态算法中，以模拟铁电材料，核心壳模型被广泛用于原子模拟中。从而通过相互作用电位（例如库仑的潜力或Lennard-Jones的潜力。新开发的算法已被用于研究原子水平的铁电现象，例如域壁。此外，已经实施了一种新方法，以考虑宏观连续性应力。因此，开发的算法不仅能够计算介电滞后，还可以计算铁电晶体的蝴蝶滞后。大多数分子静态算法不考虑温度。但是，为了模拟相变，必须考虑温度。因此，必须包括一个依赖温度的相互作用电位来扩展核心壳模型以模拟技术相关的结构和相变。在针对目标的方法学结果外，应将结果直接与其他使用非原子化方法进行模拟铁电材料的项目进行比较。