石墨烯条带的电子结构与性质:电场及长度效应

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.

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

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 Hatoms on their armchair edges (8-ZGNR) is diamagnetic, and antiferromagnetismcan be exhibited with increasing the length of nanoribbons. The antiferromagnetismand half-metallicity 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 between α- and β-spin electrons. α-Spin electrons can be induced, and showinduced charge density more readily. β-Spin electrons can escape the external field control, and show non-adiabatic properties more readily.