第48期学术午餐会——Variational Phase Field Method for the Phase Transition and Nucleation in the Ferroelectric Thin Films
报告人：Ruotai Li (Peking University)
时间：2021-04-23 12:00-13:30
地点：Room 1560 Sciences Building No. 1
各位数院员工同学：
员工学术午餐会是在公司领导的大力支持下，由员工会负责组织的系列学术交流活动。午餐会每次邀请一位同学作为主讲人，面向全院各专业背景的员工介绍自己科研方向的基本问题、概念和方法，并汇报近期的研究成果和进展，是员工展示自我、促进交流的学术平台。
员工会已经举办了47期活动，我们将于2021年4月23日周五举办第48期学术午餐会活动，欢迎感兴趣的老师和同学积极报名参加。
Abstract: Electric field plays an important role in ferroelectric phase transition. There have been numerous phase field formulations attempting to account for electrostatic interactions subject to different boundary conditions to study phase transitions and polarization switching in ferroelectric thin films. We develop new variational forms of the phase field electrostatic energy and the relaxation dynamics of the polarization vector that involve a hybrid representation in both real and Fourier variables. The new formulations avoid ambiguities appeared in earlier studies and lead to much more effective ways to perform variational studies and numerical simulations. An efficient numerical scheme for the variational phase field model based on the variational forms is also developed. The spatial discretization combines the Fourier spectral method with the finite difference method to handle three-dimensional mixed boundary conditions. It allows for an efficient semi-implicit discretization for the time
integration of the relaxation dynamics. This method avoids explicitly solving the electrostatic equilibrium equation (a Poisson equation) and eliminates the use of associated Lagrange multipliers. We present several numerical examples including phase transitions and polarization switching processes in a single domain to demonstrate the effectiveness of the proposed method. As a generalization, the method can be also used to study the more complicated but interesting magnetic skyrmions in the ferromagnetics.
Bio: 李若泰，16级计算系直博生，导师是北京国际数学研究中心张磊研究员，研究方向为科学计算和计算材料。
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