发表机构
Technical University of Kenya（肯尼亚科技大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对极性半导体中激子-声子自能计算的Fröhlich发散问题，提出宇称选择的截断方案，利用电子-空穴干涉精确处理1s内通道，大幅减少计算量，并揭示该通道对温度相关激子位移的关键作用。
AI 中文摘要
极性材料中激子-声子自能的有限温度Bethe-Salpeter计算受限于1s内散射顶点的Fröhlich发散。我们证明，对于束缚的电子-空穴对，这种发散通过电子-空穴干涉被解析消除：1s内顶点允许精确分解 $V_{\mathrm{el}}(q)=q\\,\mathcal G(q)$，其中 $\mathcal G(0)\propto(m_h-m_e)/(m_h+m_e)$，在等质量时恒为零（宇称保护）。多极干涉因子 $\mathcal I_n=\beta_e^{\\,n}-(-\beta_h)^{n}$ 决定了奇异性仅存在于偶极允许的态间通道。我们提出了一种宇称选择的激子-声子自能截断方案，其中1s内通道以可忽略的成本精确评估，收敛所需的$q$点数量减少了$10^2$-$10^3$倍。我们发现，先前被数值截断掩盖的正则化1s内通道，控制了质量不对称极性半导体中与温度相关的激子位移。
英文摘要
Finite-temperature Bethe-Salpeter calculations of exciton-phonon self-energies in polar materials are bottlenecked by the Fröhlich divergence of the intra-1s scattering vertex. We show that for a bound electron-hole pair this divergence is analytically eliminated by electron-hole interference: the intra-1s vertex admits the exact factorization $V_{\mathrm{el}}(q)=q\,\mathcal G(q)$ with $\mathcal G(0)\propto(m_h-m_e)/(m_h+m_e)$, vanishing identically for equal masses (parity protection). A multipole interference factor $\mathcal I_n=β_e^{\,n}-(-β_h)^{n}$ determines where the singularity survives-only in dipole-allowed inter-state channels. We formulate a parity-selected truncation of the exciton-phonon self-energy in which the intra-1s channel is evaluated exactly at negligible cost, converging with $10^2$-$10^3$ fewer $q$-points. We find that the regularized intra-1s channel, previously obscured by numerical cutoffs, controls the temperature-dependent exciton shift in mass-asymmetric polar semiconductors.
Comments7 pages, 5 figures, 1 table
