石墨烯条带的电子结构与性质:电场及长度效应

Effects of External Field and Nanoribbon Length on the Electronic Structure and Properties of Graphene Nanoribbons

在密度泛函理论(DFT)和含时密度泛函理论(TDDFT)的基础上对宽度上含有8个zigzag链的石墨烯条带(8-ZGNR)的基态和激发态的性质进行了理论研究,着重考察了条带长度及电场的影响.B3LYP杂化泛函的计算结果显示:在基态上,8-ZGNR的最低能量态并不具有磁性,随着长度的增加,才会显示出反铁磁的性质.静电场的加入使8-ZGNR显示出反铁磁性和半金属性.在激发态上,诱导电子会随着外激光脉冲的变化而发生移动和变化,但是相比而言,α自旋电子更容易被激发而产生较明显的诱导电子密度,而β自旋电子则更容易脱离外激光场的控制而产生非绝热现象.

We investigated the ground and excited state electronic properties of finite length zigzag graphene nanoribbons, using time-dependent density functional theory. The ground state of short graphene nanoribbons with eight H atoms on their armchair edges （8-ZGNR） is diamagnetic, and antiferromagnetism can be exhibited with increasing the length of nanoribbons. The antiferromagnetism and half-metal icity can also be shown when a static field is added. When a laser pulse is applied in the excited state, the induced electrons can move and change with the laser pulse. There exist some differences betweenα-andβ-spin electrons.α-Spin electrons can be induced, and show induced charge density more readily.β-Spin electrons can escape the external field control, and show non-adiabatic properties more readily.