Solid State and Electronic Structure of Rare Earth Metal Intercalated Graphite from First-principles Theory

Abstract

Abstract The structural arrangements of the graphite intercalates LnC6 (Ln = La, Ce, Nd and Yb) were investigated using Density Functional Theory (DFT) within the Generalized Gradient Approximation (GGA). The EuC6-type structure (AαAβ AαAβ AαA stacking) is slightly energetically preferred for La and Ce, whereas with the other rare earth metals almost the same cohesive energies are found for the three different atomic arrangements AαAαAαAαAαA. . ., AαAβ AαAβ AαA. . ., and AαAβ AγAαAβ A. . . A rather important charge transfer occurs from the metals to the carbon sheets, with the electrons partially occupying the bottom of the carbon π* band. As a consequence, a lengthening of the C-C bond lengths of ca. 0.02 Å is computed with respect to the C-C bonds in graphite. Two-dimensional metallic character is expected for LaC6 according to its band structure.