Product energy and angular momentum partitioning in the unimolecular dissociation of aluminum clusters

A previous classical trajectory simulation showed that the unimolecular dec ompositions of Al-6 and A(13) are intrinsically RRKM. In the work presented here, this study is further analyzed to determine the Al-5 + Al and Al-12 + Al product energy distributions, which are compared with the predictions of statistical theories. Orbiting transition state/phase space theory (OTS/ PST) gives distributions in excellent agreement with the trajectory results . Assuming a loose, product-like transition state gives a lower average pro duct translational energy, <E-t> than what is found with the orbiting trans ition state. Including anharmonicity, in the calculation of the product vib rational density of states, increases the energy partitioned to product vib ration. The Engelking model for cluster decomposition overestimates <E-t>. One Klots model gives an inaccurate <E-t>, but a second model more firmly r ooted in phase space theory performs quite well. The Engelking model, for d educing the cluster dissociation energy from the measured <E-t>, does not g ive accurate results for Al-6 and Al-13 dissociation.