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New method for approximate Hartree‐Fock calculations using density approximations and coulomb field corrections. II
Author(s) -
Noack WolfEckart
Publication year - 1980
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.560170608
Subject(s) - dipole , approximation error , chemistry , coulomb , atomic physics , binding energy , field (mathematics) , hartree–fock method , basis (linear algebra) , computational chemistry , physics , quantum mechanics , mathematics , mathematical analysis , geometry , electron , pure mathematics
The HF approximation method that was outlined in Paper I is tested with respect to several molecular properties. Three different levels of approximation a , b , and c are considered. Satisfactory results—compared to corresponding “exact” HF calculations—are obtained with the STO ‐3G basis and the approximation level a . At this level the error in the binding energy is 0.001–0.025 a.u. for all considered molecules which contain up to six first‐row atoms as, e.g., cyclopentanone (C 5 OH 8 ). The error in the reaction energies considered here is about 4 kcal/mol (the maximal error is 9 kcal/mol). Orbital energies, dipole moments, gross charges, equilibrium geometries, and barriers to internal rotation are well reproduced by the approximation method at all three levels.