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Cation‐ligand interactions: Ab Initio SCF studies of the binding properties of alkali, alkaline‐earth, and ammonium ions
Author(s) -
Pullman A.,
Berthod H.,
Gresh N.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560100806
Subject(s) - alkali metal , chemistry , basis set , ion , ab initio , delocalized electron , computational chemistry , binding energy , ligand (biochemistry) , alkaline earth metal , atomic orbital , chemical physics , atomic physics , physics , density functional theory , quantum mechanics , organic chemistry , biochemistry , receptor , electron
SCF ab initio computations of water‐cation interactions are reported for Li + , Na + , K + , Mg ++ , Ca ++ , and NH 4 + in view of exploring the utilizability (if any) of relatively small basis sets in this area. Starting with an STO 3G standard set on both the ligand and the cation, a careful scrutiny using a decomposition of the binding energy into its electrostatic, exchange, and delocalization components shows that the poor performance of this basis is due partly to the poor intrinsic representation it gives of the two entities, partly to the overavailability of empty orbitals on the ion. Successive improvements of the cation basis and of the water representation up to the 4–31G level are discussed in the same light and show that the performances of a split basis in this area can be surpassed by those of a good minimal set. General interrelations between the alkali and alkaline‐earth ions are demonstrated in the light of the energy decompositions.