Abstract
Density functional calculations with simulated annealing have been performed to determine the structures and relative stabilities of stable isomers of seven-membered molecules containing elements of groups V (phosphorus, arsenic) and VI (sulfur, selenium, and tellurium). Particular attention is focused on structures related to P4S3 and P2S5, including the families PnAs4−nS3−mSem and P4SnTe3−n. We show that the bonding trends in all these molecules can be understood in terms of transferable bond energies.