发表机构
Portland State University（波特兰州立大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究超越准粒子近似的声子谱函数与热输运，引入自洽谱函数框架，通过全频率分布表示声子并修正自能内线，应用于HgTe时拓宽声子谱、激活散射通道、降低热导率，验证结果并确立其为连接两种理论的桥梁及可推广框架。
AI 中文摘要
非简谐晶格动力学塑造声子谱和热输运，但第一性原理线宽计算通常假定具有明确定义频率的声子准粒子。我们引入一个自洽谱函数框架，用其全频率分布表示每个声子，并使用所得谱修正三声子泡自能的内线。该方法在同等基础上自洽确定自能的实部和虚部，消除用于强制能量守恒的外部选定的展宽参数，将晶格动力学和热输运计算扩展到准粒子近似之外。应用于闪锌矿HgTe时，自洽显著拓宽声学和光学声子谱，激活单次准粒子计算中无法进入的散射通道，将晶格热导率降低约五倍至实验尺度，同时再现其温度依赖性，且无需明确调用高阶相互作用。模式分辨谱函数进一步通过直接分子动力学模拟的功率谱进行验证。这些结果确立自洽谱函数为准粒子微扰理论和完全动力学模拟之间的实用桥梁，并提供一个易于推广到高阶非简谐过程的框架。
英文摘要
Anharmonic lattice dynamics shapes phonon spectra and thermal transport, yet first-principles linewidth calculations typically assume phonon quasiparticles with sharply defined frequencies. Here, we introduce a self-consistent spectral function framework that determines interacting phonon spectral functions by dressing the internal lines of the three-phonon bubble self-energy with the spectra generated by the same interaction. The method self-consistently determines the real and imaginary parts of the self-energy on equal footing, eliminates the need for externally chosen smearing parameters to enforce energy conservation, and extends lattice dynamics and thermal transport calculations beyond the quasiparticle approximation. Applied to zincblende HgTe, self-consistency substantially broadens acoustic and optical phonon spectra, activates scattering channels inaccessible in the one-shot quasiparticle calculation, and reduces the lattice thermal conductivity by approximately a factor of five to the experimental scale while reproducing its temperature dependence, without explicitly invoking higher-order interactions. Mode-resolved spectral functions are further validated against the power spectra from direct molecular dynamics simulations. These results establish self-consistent spectral functions as a practical bridge between quasiparticle perturbation theory and fully dynamical simulations, and provide a framework readily generalizable to higher-order anharmonic processes.
