Theoretical Study Of Carbon Doping Effect On Structures And Properties Of Beryllium Clusters

The global minimum structures of the carbon-doped Ben(n = 1–12)clusters are obtained at the B3PW91/6-311+G(d)level and compared with those of pure beryllium clusters.It is found that the carbon dopant prefers to locate on the periphery of the host Ben cluster and tends to be tetra-coordinated.The only exception here is Be6 C where the carbon atom is connected to three Be atoms.This may be attributed to the high stability of Be6,whose octahedral structure would be broken if it combined with the carbon atom through four Be-C bonds.It has been also found that all the Ben C(n= 1–12)clusters have singlet spin ground states except that Be C favors a triplet spin state.The evolution of electronic and energetic properties of Ben C with cluster size is studied using the QCISD(T)method.Results show that the introduction of carbon-doping in beryllium clusters strengthens intracluster interaction.Besides,Be3 C and Be8 C exhibit particular stability and are considered as magic number clusters in the Ben C series.Molecular orbital(MO)analysis indicates that both clusters have fully-filled electron shells,whereas the contribution of carbon atomic orbital leads to MO energy level disorder relative to pure beryllium clusters.The 2S level of Be8 C is lower than,and being filled prior to,three 1D orbitals.As for the Be3 C cluster,the carbon dopant also leads to lower 2S orbital energy level than those of 1D orbitals.