Clusters of ionic molecules: Hexamers of LiF, LiOH and LiNH (2).

Lithium compounds are known to associate in solvents, in the crystal and even in the gas phase. The detailed study of such compounds provides a convenient framework to understand the nature of the bonding in small clusters of these predominantly ionic species. Recent experimental efforts using a variety of techniques have yielded a wealth of information about dimers, trimers, tetramers and hexamers of many lithium compounds. However, detailed theoretical understanding in many of these systems is lacking. In this work, we have performed accurate quantum chemical calculations to study the structures and energies of the hexamers of LiF, LiOH and LiNH(2). Large basis sets including diffuse and polarization functions have been used in these calculations. Distorted octahedral structures are found to be significantly more stable than planar hexagonal- type structures for all three hexamers.