基于密度泛函理论的单层氢化石墨烯特性分析

Characteristic analysis of single-layer hydrogenated graphene based on density functional theory

本文采用密度泛函理论的第一性原理方法,研究了不同尺寸H-graphene的稳定性、HOMO-LUMO能隙以及电子激发态.研究结果表明,对于C_(16)H_(10)、C_(30)H_(14)、C_(48)H_(18)、C_(70)H_(22)、C_(96)H_(26)、C_(126)H_(30)计算的比结合能,C_(126)H_(30)相比C_(16)H_(10)的比结合能增长23.9%,且比结合能随着H-graphene尺寸扩大而增加,意味着稳定性不断提高.通过对HOMO-LUMO能隙分析发现,在较小尺寸的H-graphene中,由于量子效应起主要作用,因此出现了较大的HOMO-LUMO能隙,且随着H-graphene团簇尺寸的增加,能隙逐渐缩小可以看出,对于无限大的H-graphene团簇中,HOMO-LUMO能隙无限趋近于零(相当于零带隙),其电子性质与纯石墨烯相似.通过分析C_(16)H_(10)、C_(30)H_(14)、C_(48)H_(18)、C_(70)H_(22)激发态以及了吸收光谱,发现随着尺寸的扩大,吸收光谱发生红移,为石墨烯在电子器件领域的应用提供理论基础.

This paper uses the first-principles method of density functional theory to study the stabilities,HOMO-LUMO energy gaps,and electronically excited states of different sizes of H-graphene.The results show that in the calculated specific binding energy of C_(16)H_(10),C_(30)H_(14),C_(48)H_(18),C_(70)H_(22),C_(96)H_(26)and C_(126)H_(30),the specific binding energy of C_(126)H_(30)is larger by 23.9%than that of C_(16)H_(10),and it increases with the expansion of the H-graphene size,which means that the stability is continuously improved.Through the analysis of the HOMO-LUMO energy gap,it is found that in the smaller size of H-graphene,due to the quantum effect playing a major role,a larger HOMO-LUMO energy gap appears,and as the size of the H-graphene cluster increases,the energy gap gradually shrinks.It can be seen that for the infinite H-graphene clusters,the HOMO-LUMO energy gap is infinitely close to zero(equivalent to zero bandgaps),and its electronic properties are similar to those of pure graphene.Through the analysis of C_(16)H_(10),C_(30)H_(14),C_(48)H_(18),C_(70)H_(22)excited states,and absorption spectra,it is found that as the size increases,the absorption spectrum has a redshift,providing a theoretical basis for the application of graphene in the field of electronic devices.