The Phonon Quasiparticle Approach for Anharmonic Properties of Solids

活动时间： 12月27日09时30分       

地            点  ： 线上（腾讯会议 ID: 799 372 736），会议链接：https://meeting.tencent.com/dm/6tdOYgriHuWi

讲座内容：

In crystalline materials, anharmonicity is crucialin understanding several phonon-driven phenomena, e.g., high-temperaturestructure stabilization, phase transition especially close to meltingtemperatures, thermal conductivity, etc. Anharmonicity can be characterized bythe intrinsic temperature dependence of phonon frequencies, usually (but notalways) increasing with temperature. As such, the calculation oftemperature-dependent phonon dispersions incorporating anharmonic effects iscritical for predictive studies of vibrational, thermodynamic, and latticetransport properties. In this talk, I will introduce the phonon quasiparticleapproach, combining molecular dynamics (MD) simulations and lattice dynamicscalculations to address phonon anharmonicity. The method invokes the concept ofphonon quasiparticle characterized by two quantities, renormalized frequencyand lifetime. These quantities can be extracted from the mode-projectedvelocity autocorrelation function sampled by MD simulations. In principle,anharmonic interactions are captured to infinite order in perturbation theory.Anharmonic phonon dispersions can be obtained by Fourier interpolation of therenormalized frequencies, from which vibrational free energy, phase boundary,and thermodynamic properties can be further computed. Quasiparticles’ lifetimescan also be used to calculate lattice thermal conductivity using the linearizedBoltzmann transport equation.

主讲人介绍：

张祯，哥伦比亚大学应用物理专业博士生。2012~2016年就读于南开大学，获物理学学士学位。目前主要研究方向为使用第一性原理计算模拟材料与地球矿物在高温高压下的热力学与热输运性质，主要研究方法为声子准粒子方法，第一性原理分子动力学，大规模并行计算等。已在国际知名学术期刊Physical Review B，Computer PhysicsCommunications等杂志上发表多篇SCI论文。曾在APSMarch Meeting，AGU Fall Meeting等国际会议上做邀请报告。

发布时间：2021-12-24 22:34:41