Ab initio studies of O2−(H2O)n and O3−(H2O)n anionic molecular clusters, n≤12

摘要

An ab initio study of gaseous clusters of O and O withwater is presented. Based on thorough scans of configurational space, wedetermine the thermodynamics of cluster growth. The results are in goodagreement with benchmark computational methods and existing experimentaldata. We find that anionic O(HO) and O(HO)clusters are thermally stabilized at typical atmospheric conditions for atleast = 5. The first 4 water molecules are strongly bound to the aniondue to delocalization of the excess charge while stabilization of more than 4HO is due to normal hydrogen bonding. Although clustering up to 12HO, we find that the O and O anions retain at least ca. 80 %of the charge and are located at the surface of the cluster. The Oand O speicies are thus accessible for further reactions.We consider the distributions of cluster sizes as function of altitude beforefinally, the thermodynamics of a few relevant cluster reactions are considered.