| The studies of the interactions of CN-containing molecules with transition metalsurfaces are an important topic in the domain of many sciences, for example, incatalyze, electrochemistry, environmental conservation and chemical defense areas,etc. So,the studies of adsorbed CN-containing molecules on metal surfaces withtheoretically not only help us to more understand the their bonding mechanism andreactivity in catalysis and other surface phenomena, but also advance the developmentof solid theoretical chemistry and correlative experimental method. In this paper,based on the optimization of cluster model and basis bet, the adsorption anddissociation of a series of CN-containing molecules on transition metal surfaces isstudied by using the density functional method. The main investigative contents are asthe following: 1. The adsorption of OCN, CN and O on Cu (100) surface is studied. It shows thatthe most favorable adsorption mode is N-down with OCN axis perpendicular to thesurface, C-down on top site with CN axis perpendicular to the surface, and O at the4-fold hollow site for OCN, CN, and isolated oxygen atom absorbed on the surface,respectively. These results are in excellent agreement with the experimentation. Forthe coabsorption of CN and O on Cu (100), the calculated results first show that theformation of surface OCN is stably absorbed on the Cu surface, and the correspondingcatalyze mechanism is obtained. The interaction of CN and O2 on Cu (100) surfacemay be spontaneously produce OCN molecule. 2. For the adsorption of HCN, HNC, CNH2 and HCNH on Cu (100) surface, thecalculated results show that both HCN and HNC are weakly absorbed on the top siteof Cu (100) with the molecular axis perpendicular to the surface, and more favorableover other sites. These results are in good agreement with the experimental reports.For the coadsorption of HCN and CO on the Cu (100) surface, the vibrational VIfrequencies of CN and CO all shift to the lower wave number. Both CNH2 and HCNHare all stably absorbed on the surface with the adsorption model, however, thedifference of calculated adsorption energy between CNH2 and HCNH is quite small. 3. For CN, HCN and HNC adsorbed on the Pt surface, the most favorableadsorption mode and stretching frequencies are obtained, and in good agreement withthe experiment. The calculated results show that the difference of adsorption energybetween HCN and HNC is obvious, and it may be a possible method for removing thepoison gas. For HCN absorbed on Pt (111) surface with the parallel adsorption mode,the C-N bond length is lengthened, and indicates that dissociation of HCN may beproduce the CNad and Had species. 4. The studies of the C-down and N-down model of CN absorbed on the top sites ofM (100) (M=Ni, Pd, Pt, Cu, Ag, Au) surfaces are systemically compared. Thecalculated results show that CN can be stably absorbed on the surfaces, and the chargetransfers from the surfaces to the CN molecule. For the same surface, the C-down ismore stable than N-down. The bond of C-down is strengthened whereas the N-downone is weakened upon chemisorption based on shift to higher or lower frequencies,respectively, with respect the stretching frequency of the free absorbate. 5. The possible geometries of Fe(HCN)n (n = 1~6) compounds are studied. The +structure and ground state, the sequential incremental interaction energy,dissociation energy, enthalpy and Gibbs free energy, and frequencies of eachfragmental ion are obtained with n = 1～5. For the compound Fe(HCN)6 , the +possible geometry was not obtained. The results are all in good agreement with theexperiments. The bond length of Fe–N is lengthened with the increase of cluster size,and the strength of Fe+–N coordination bond varies nonmontonically as increasing thenumber of ligands. The Fe+–N bond of Fe(HCN)2 is the strongest in all compo...
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