Abstract: Using density function theory (DFT),the geometries,electron structure,vibration frequency and enthalpy variation of the chemical reaction of (XN)4R4 (X=C,Si,Ge;R=H,CH3,NH2,OH) and its precursor compound (RXNR)2 have been calculated at B3LYP/6-311G level.The results show that (RCN)4 is more stable than (CNR)4.EZP is the smallest when R=H and the largest as R=CH3,and decreases generally as R is C,N and O.

Key words: (XN)4R4 cubic clusters, Density function theory(DFT) method, 　Structure, Chemical bond