Abstract
The interaction potential of a atom with a graphene layer is calculated using the local density approximation to the density functional theory. Two configurations corresponding to different separations between in neighboring supercells were considered to determine the effect of interaction on the binding of to graphene. The equilibrium position of is not affected by the interaction and remains the same in both cases. It is equal to above graphene with the at the center of a hexagonal ring formed by the carbon atoms. However, the binding energies differ substantially in the two configurations. The binding energy of is in configuration A when the separation in adjacent supercells is The binding energy is in configuration B corresponding to a separation between adjacent atoms. There is substantial charge transfer from both lithium and carbon atoms (including those that do not surround the lithium) to a region between the and graphene at the minimum energy configuration. The interaction potential for both configurations can be fitted to a sum of a screened Yukawa potential and a linear superposition of power-law functions of type , where is an integer. The density functional theory underestimates the attractive contribution of dispersion forces for large separations. The attractive interaction potential calculated for positions much greater than the equilibrium distance from graphene may therefore need to be corrected.
- Received 6 February 2004
DOI:https://doi.org/10.1103/PhysRevB.70.125422
©2004 American Physical Society