Magnitude of contribution of AOs and contribution of electron in each occupied molecular orbital of ferrocene and nickelocene based on eigenvalues, eigenvectors and population analysis have been studied. The 3D structure of both ferrocene and nickelocene were drawn on workspace software associated with CAChe and their geometries were optimized with DFT method. The evaluation of eigenvalues, eigenvectors and other parameters were done by using molecular mechanics with EHT option. The study has concluded that the first ten MOs in ferrocene and eight MOs in nickelocene have contribution from 2pz orbitals of carbon of C5H5¯ and 3d orbitals of metal. The total involvement in respect of bonding between C5H5¯ and the metal orbitals as derived from coefficient value is 20.3087 in ferrocene and 23.5716 in nickelocene. The population analysis shows that only 2pz orbitals of carbon of C5H5¯ and 3d orbitals of metal provide electrons to MOs of ferrocene or nickelocene.
