Thermal isomerization in Cs4Cl3-

Theoretical electronic structure studies have been carried out to show that the recently observed thermal isomerization in Cs4Cl3- clusters is due to three energetically close structures with a cuboid, a ladder, and an octagonal ring arrangement. It is found that the electronic excited states can serve as a fingerprint for identification of these structures. By calculating total energies and electronic excited states, we identify the cuboid as the most stable geometry. The vibrational spectra of the isomers are shown to be marked by low-energy modes which enable them to isomerize at ordinary temperatures.