STABILITY AND STRUCTURE OF RARE-GAS IONIC CLUSTERS USING DENSITY-FUNCTIONAL METHODS - A STUDY OF HELIUM CLUSTERS

Several modelings of exchange and correlation forces which can be carr ied out using density functional theory (DFT) methods have been analyz ed to study their efficiency and reliability when evaluating possible competing structures of helium ionic clusters of increasing size. This study examines He-n(+) systems with n from 1 to 7 and compares the pr esent calculations with earlier evaluations that used more conventiona l, and more computationally intensive, methods with configuration inte raction (CI) approaches. The present results indicate that it is indee d possible to strike a fruitful balance between reduction of computati onal times and quality of the ensuing structural information. (C) 1996 John Wiley & Sons, Inc.