Rcaction mechanism between Mg(NH₂)₂ and LiH are investigated with a B3LYP method of density functional theory. Geometries and harmonic vibration frequencies of reactants,intermediates,transition states and products are calculated at B3LYP/6-311G(d,P) level.Vibration analysis and intrinsic reaction coordinates(IRC) calculation at the same level are applied to validate connection of stationarv points. It indicates that the reaction has three stages.They are the first step of hydrogen substitution,the second step of hydrogen substitution and isomerization after removal of hydrogen.There are two pathways, in which a channel of the second step of alignment hydrogen suhstitution reaction is the main channel.The two hydrogen atoms in H₂ released are from Mg(NH₂)₂ and Lilt.

A fractal model of coarse surface of SiC by using structure function is presented.Three parameters rms roughness Δ,fractal dimension D,and correlative length L are used to describe the covariance function of surface height.The method calculating these parameters is also given.With the present model,one can calculate the coarse dispersion of SiC/SiO₂ fractal interface to channel electrons.