原子非简谐振动对石墨烯吸附系统电荷分布的影响

Influence of the atomic anharmonic vibration on charge distributions of graphene adsorption system

摘要:

建立了石墨烯吸附原子系统的物理模型，考虑到原子的非简谐振动和电子—声子相互作用，计算了吸附原子与石墨烯原子的相互作用能，用统计物理理论和方法，得到在石墨烯上吸附原子的概率和金属原子电荷填充数随温度变化的解析表示式. 以碱金属为例，探讨了电子—声子互作用和原子非简谐振动对电荷填充数的影响. 结果表明：石墨烯吸附系统的电荷填充数随吸附原子距离的增大而线性地减小，随温度的升高和电子—声子相互作用能的增大而非线性地增大；若不考虑非简谐振动，则电荷填充数与位置、温度等无关. 温度愈高、电子—声子相互作用能愈小，非简谐效应愈显著.

Abstract:

In this paper, a physical model of graphene adsorption system is established. The interaction energy between graphene atoms and adatoms is calculated in the case of considering the anharmonic vibration of the atom and the electron-phonon interaction. By means of the statistical physics theory and method, we obtain the probability of adsorption adatoms and the temperature-dependence analytic equation of the number of mental atoms charge filling. Taking alkali metals as an example, we discuss the effect of the electron-phonon interaction and the atomic anharmonic vibration on the number of charge filling. The results show that the charge filling numbers of graphene adsorption system decrease linearly with the enlargement of distances of adatoms and increase nonlinearly with the increase of temperature and electron-phonon interaction energy. If the anharmonic vibration is neglected, the number of charge filling is independent of distance and temperature etc. The anharmonic vibration is more obvious when the temperature becomes higher or the electron-phonon interaction energy becomes smaller.