COST-EFFECTIVE CALCULATION OF MOLECULAR CHARGE-DISTRIBUTIONS AND GAS-PHASE DEPROTONATION ENERGIES USING DENSITY-FUNCTIONAL METHODS

Major advances have been made in density functional theory and linear scaling methods. However, routine application of these methods to larg er systems possessing no symmetry; still remains difficult. Moreover, no clear standard exists for the use of small basis sets in the calcul ation of atomic or molecular properties with density. functional metho ds. In this work an evaluation is made of the performance of different density functional methods for small and often used basis sets. Depro tonation energies are calculated for a series of small compounds and c ompared with high-level quantum chemical calulations. Furthermore, ato mic populations calculated with these methods are compared with high-l evel results. The results show that the use of density functional calc ulations with smaller basis sets is justified for calculations on larg er systems, retaining relatively good accuracies. (C) 1997 Published b y Elsevier Science B.V.