单层石墨烯水分子吸附对其光学性质的影响

用基于第一性原理中的密度泛函理论MS软件对水分子吸附在单层石墨烯表面进行计算,使用广义梯度近似和周期性平面模型,得到不同数量的水分子吸附在石墨烯表面上的吸附能,并且计算了相对应的光学性质.得到的结果是吸附能很小,主要是范德瓦尔斯相互作用.石墨烯具有高疏水性,水分子在石墨烯表面对石墨烯的电子结构几乎没有作用,吸附不同个数的水分子后对石墨烯的光学性质有一定影响,其中吸附单个水分子后变化并不明显,吸附2或3个水分子后吸收率和光电导率略有下降;折射率和消光率下降不明显,说明吸附水对石墨烯的透明度影响不大;介电函数的实数部分变化趋于平缓,虚数部分有明显下降;能量损失增加.

Effects on Optical Properties of the Adsorption of Water Molecules on Graphene

The first-principles based on the density functional theory are applied to study the effects of water molecules adsorption on graphene. Using the generalized gradient approximation and periodic plane model, the adsorption energy and optical properties of different water molecules adsorbed on graphene are systematically investigated. The results show that the adsorption energy is very small due to the van der Waals interactions between water molecules and graphene. Graphene is highly hydrophobic and adsorbed water molecules have very little effect on the electronic structure of graphene. Adsorption of water molecules has influences on the optical properties of graphene is as follows: The absorption rate and conductivity fell slightly when two or three water molecules adsorbed on graphene, but it is nearly unchanged as for adsorption of one water molecule. The decline of refractive index and extinction rate is not remarkably, which shows water has little effect on the transparency of graphene. The curves of dielectric function becomes smooth and slow in real number part but goes down in imaginary part, and the energy loss increases.