Hs. Cheng et al., Hydrogen adsorption in potassium-intercalated graphite of second stage: Anab initio molecular dynamics study, J PHYS CH B, 105(3), 2001, pp. 736-742
We present an ab initio molecular dynamics study on hydrogen adsorption in
potassium-intercalated graphite of second stage. The simulation utilizes th
e ultrasoft pseudopotenals plane wave method under local density functional
approximation. The optimized lattice structures and the calculated H-2 ads
orption energy are in excellent agreement with experiments. The simulation
also well reproduces the previously observed lattice expansion due to H-2 u
ptake. The dynamics investigations reveal that not only the adsorbed hydrog
en molecules but also the intercalated potassium atoms are highly mobile an
d assume a variety of two-dimensional configurations. The hydrogen dynamics
is essentially chaotic within a layer of about 1.4 Angstrom, thickness cen
tered between the graphite sheets, with a closest C-H distance of about 2.2
Angstrom.