Citation
Conesa Cegarra, José Carlos and Tablero Crespo, César and Wahnón Benarroch, Perla
(2004).
First principles calculations of electronic structures and metal mobility of NaxSi46 and NaxSi34 clathrates.
"The Journal of Chemical Physics", v. 120
(n. 13);
pp. 6142-6151.
ISSN 0021-9606.
https://doi.org/10.1063/1.1650303.
Abstract
Energetics, geometry, electronic band structures, and charge transfer for NaxSi46 and NaxSi34
clathrates with different degrees of cavity filling by sodium, and the mobility of the Na atom inside
the different cavities are studied using first principles density functional calculations within the
generalized gradient approximation. The stabilization of the clathrate lattice and the cell volume
variation upon the inclusion of Na ~which appears to move easily in the larger cavities of NaxSi34 ,
thus justifying the experimental observations! are discussed in connection with the onset of the
repulsion between Na and Si for distances shorter than ;3.4 Å. For all degrees of filling of the
different cavities examined we find that the electron population of the s orbitals in the partially
ionized Na atoms increases with a decrease in the size of the cavity, and that the Na states contribute
significantly to the density of states at the Fermi level and thus influence the properties of these
compounds