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Geometry, basis set, and correlation energy dependence of computed protonation energies of imino bases
Author(s) -
Del Bene Janet E.
Publication year - 1984
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.540050416
Subject(s) - protonation , basis set , chemistry , valence (chemistry) , electronic correlation , hartree–fock method , gaussian orbital , computational chemistry , nitrogen , basis (linear algebra) , atomic physics , molecule , geometry , physics , ion , density functional theory , mathematics , organic chemistry
The nitrogen protonation energies of the imino bases HNCH R , where R is H, CH 3 , NH 2 , OH, and F, have been evaluated to determine the dependence of absolute and relative protonation energies on geometry, basis set, and correlation effects. Reliable absolute protonation energies require a basis set larger than a split‐valence plus polarization basis, the inclusion of correlation, and optimized geometries of at least Hartree–Fock 4‐31G quality. Consistent relative protonation energies can be obtained at the Hartree–Fock level with smaller basis sets. Extending the split‐valence basis set by the addition of polarization functions on all atoms decreases the computed absolute Hartree–Fock nitrogen protonation energies of the imino bases HNCH R except when R is F, but increases the oxygen protonation energies of the carbonyl bases OCH R .