A new structural force field for metallocenes is presented, searched with a cartesian stochastic search routine and energy barriers have been computed by scanning the which involves harmonic bonding potentials from the metal center to each of the carbon atoms, no angular potentials pseudo-torsional angles involving the centroids of the two Cp rings. The computed energy barriers are smaller than those around the metal ion, inter-ligand 1,3-non-bonded interactions, and transferable parameters for the ligand determined experimentally, but the predicted increase in transition energy upon substitution of the Cp rings is in backbones. The model has been parameterized for ferrocene, ruthenocene, and osmocene derivatives and the force field agreement with experiment and the torsional angles for the minimum structures are computed accurately. It is suggested has been validated with relevant structures from the CSD files (Fe: 34, Ru: 10, Os: 2). The conformational space that the underestimated barrier height is due to the neglect of solvation. [rotation of the Cp (cyclopentadienyl) rings] has been with other classes of ligands such as benzene or allyl [a]