Holstein分子晶体模型能带结构的温度依赖性

研究了温度对Holstein分子晶体模型能带结构的影响,结果表明固体的能带宽度和禁带宽度都与电子和热声子相互作用以及热膨胀密切相关.对一维Li原子品格链,在所选定的参数下,1s和2s的能带宽度随着温度的增加而变窄,两带之间的禁带宽度变宽,这些结果与实验结果在定性上是一致的.显然,研究能带结构的温度依赖性对于理解固体的光学和输运性质都是十分重要的.

Temperature Dependence of the Energy-Band Structure for the Holstein Molecular-Crystal Model

We study the influences of the temperature on the energy-band structure for the Holstein molecular-crystalmodel. We show that the energy-band width and the energy-gap width of a solid are relevant to both the interaction be-tween an electron and thermal phonons and to thermal expansion. For a one-dimensional Li atom lattice chain, under thechosen parameters, the width of the 1s and 2s energy bands narrows as the temperature increases and the energy-gap widthbetween the two bands widens. These results agree qualitatively with those observed experimentally. Studying temperaturedependence of the energy-band structure is of great importance for understanding optical and transporting characteristicsof a solid.