ENERGETICS OF THE ADSORPTION AND DIFFUSION
OF HYDROGEN MOLECULES IN A (001) PLATE
OF NANOCRYSTALLINE ALUMINUM

A. L. Zaitsev, Yu. M. Pleskachevskii,
and S. A. Chizhik

UDC 539.1:536.36

The energetics of the adsorption and diffusion of hydrogen 
molecules in the surface of an Al plate bounded by the (001) atomic 
plane has been investigated by the density-functional method. The 
spatial configuration of hydrogen atoms and surface layers of the 
plate corresponding to the most stable structures was determined. 
It has been established that the energies of the physical and che-
mical adsorptions of hydrogen are equal to -0.049 eV and -0.080 eV 
respectively. It is shown that, as a result of the chemisorption, 
two stable spatial configurations with energies differing by 0.33 
eV are formed. A bridge arrangement of hydrogen atoms between the 
apical atoms of aluminum is characterized by a minimum energy. The 
energy barrier of transformation of a hydrogen molecule from the phy-
sical into the chemisorbed state comprises 0.438 eV. An H2 molecule
does not dissociate completely in the process of adsorption and 
diffusion. On the surface and in the bulk of the metal being considered 
there arise diagonal-chain structures, in which the distance between 
the hydrogen atoms does not exceed 2.86 Å.

A. V. Luikov Heat and Mass Transfer Institute, National 
Academy of Sciences of Belarus, 15 P. Brovka Str., Minsk, 220072, 
Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, 
No. 1, pp. 157-164, January-February, 2008. Original article 
submitted August 1, 2007.