使用多体摄动理论研究了碱土金属氧化物CaO的电子激发态和光吸收谱.运用GW近似方法来改进DFT对电子交换关联的处理,并计算了CaO电子能带结构.考虑到电子与空穴的相互作用,运用二粒子格林函数理论来求解Bethe-Salpeter方程,计算电子-空...使用多体摄动理论研究了碱土金属氧化物CaO的电子激发态和光吸收谱.运用GW近似方法来改进DFT对电子交换关联的处理,并计算了CaO电子能带结构.考虑到电子与空穴的相互作用,运用二粒子格林函数理论来求解Bethe-Salpeter方程,计算电子-空穴激发态,并在此基础上计算光吸收谱.计算结果 CaO能隙为7.0 e V,与实验结果 7.1 e V符合很好;并且CaO光吸收谱的理论结果与实验数据也相符合.展开更多
We show that a current-carrying coherent electron conductor can be treated as an effective bosonic energy reservoir involving different types of electron–hole pair excitations.For weak electron–boson coupling,hybrid...We show that a current-carrying coherent electron conductor can be treated as an effective bosonic energy reservoir involving different types of electron–hole pair excitations.For weak electron–boson coupling,hybrid energy transport between nonequilibrium electrons and bosons can be described by a Landauer-like formula.This allows for unified account of a variety of heat transport problems in hybrid electron–boson systems.As applications,we study the non-reciprocal heat transport between electrons and bosons,thermoelectric current from a cold-spot,and electronic cooling of the bosons.Our unified framework provides an intuitive way of understanding hybrid energy transport between electrons and bosons in their weak coupling limit.It opens the way of nonequilibrium reservoir engineering for efficient energy control between different quasi-particles at the nanoscale.展开更多
The electron-hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots （Cdots） is still not clear. In this study,...The electron-hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots （Cdots） is still not clear. In this study, we have developed a simple and efficient one-step strategy to synthesize luminescent Cdots using the pyrolysis of oleylamine. The sp^2 clusters of a few aromatic rings are responsible for the observed blue photoluminescence. The size of these clusters can be tuned by controlling the reaction time, and the energy gap between the π-π＊ states of the sp^2 domains decreases as the sp^2 cluster size increases. More importantly, the strong electron-hole exchange interaction results in the splitting of the exciton states of the sp^2 clusters into the singlet-bright and triplet-dark states with an energy difference ΔE, which decreases with increasing sp^2 cluster size owing to the reduction of the confinement energy and the suppression of the electron-hole exchange interaction.展开更多
文摘使用多体摄动理论研究了碱土金属氧化物CaO的电子激发态和光吸收谱.运用GW近似方法来改进DFT对电子交换关联的处理,并计算了CaO电子能带结构.考虑到电子与空穴的相互作用,运用二粒子格林函数理论来求解Bethe-Salpeter方程,计算电子-空穴激发态,并在此基础上计算光吸收谱.计算结果 CaO能隙为7.0 e V,与实验结果 7.1 e V符合很好;并且CaO光吸收谱的理论结果与实验数据也相符合.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0403501)the National Natural Science Foundation of China(Grant No.21873033)the Program for HUST Academic Frontier Youth Team。
文摘We show that a current-carrying coherent electron conductor can be treated as an effective bosonic energy reservoir involving different types of electron–hole pair excitations.For weak electron–boson coupling,hybrid energy transport between nonequilibrium electrons and bosons can be described by a Landauer-like formula.This allows for unified account of a variety of heat transport problems in hybrid electron–boson systems.As applications,we study the non-reciprocal heat transport between electrons and bosons,thermoelectric current from a cold-spot,and electronic cooling of the bosons.Our unified framework provides an intuitive way of understanding hybrid energy transport between electrons and bosons in their weak coupling limit.It opens the way of nonequilibrium reservoir engineering for efficient energy control between different quasi-particles at the nanoscale.
文摘The electron-hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots （Cdots） is still not clear. In this study, we have developed a simple and efficient one-step strategy to synthesize luminescent Cdots using the pyrolysis of oleylamine. The sp^2 clusters of a few aromatic rings are responsible for the observed blue photoluminescence. The size of these clusters can be tuned by controlling the reaction time, and the energy gap between the π-π＊ states of the sp^2 domains decreases as the sp^2 cluster size increases. More importantly, the strong electron-hole exchange interaction results in the splitting of the exciton states of the sp^2 clusters into the singlet-bright and triplet-dark states with an energy difference ΔE, which decreases with increasing sp^2 cluster size owing to the reduction of the confinement energy and the suppression of the electron-hole exchange interaction.
