The dissociative chemisorption of molecular hydrogen on lithium clusters

The interaction of a hydrogen molecule with a surface simulated by eight lithium atoms is examined by use of ab initio SCF-MO calculations in an STO-3G basis. Three surface configurations are employed, one in which all eight lithium atoms form a surface plane and the other two configurations contain six lithium atoms in one plane and the remaining two Li are above and below the plane, respectively. Two variables are examined in some detail, namely the distance of the molecule from the surface and the internuclear separation in the molecule. For a planar configuration an activation barrier for dissociative chemisorption of approximately 90 kcal/ mole is found for the H2 molecule approximately 1.4 A from the surface. (Auth.)