title: Treatment of ionic species in force-field calculations: sulfate and carboxylate groups in carbohydrates.
abstract: Ab initio computations with different basis sets (up to 6-31 + G* *) on methylsulfate and N-methylsulfate anions and on the ionic and neutral forms of acetic acid are presented. The atomic charges for the O-sulfo group, computed using the Merz-Kollman method at the highest level of theory, were inserted in a MM2-derived force-field; its current parametrization affords a 0.22 A root-mean-square deviation with respect to five crystal structures of sulfated monosaccharides.
authors.affiliation: 1st Chimica Macromolecole del CNR, Milano, Italy.
authors.forename: D R
authors.initials: DR
authors.lastname: Ferro
authors.forename: P
authors.initials: P
authors.lastname: Pumilia
authors.forename: A
authors.initials: A
authors.lastname: Cassinari
authors.forename: M
authors.initials: M
authors.lastname: Ragazzi
mesh_terms: D000085:Acetates; D019342:Acetic Acid; D000838:Anions; D002236:Carbohydrate Conformation; D008958:Models, Molecular; D008962:Models, Theoretical; D008968:Molecular Conformation; D013431:Sulfates; D013463:Sulfuric Acid Esters
chemical_list: D000085:Acetates; D000838:Anions; D013431:Sulfates; D013463:Sulfuric Acid Esters; D019342:Acetic Acid; C033522:methyl sulfate