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Optimized linear combinations of simple exponentials for atomic systems
Author(s) -
Solomon C. E.
Publication year - 1971
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.560050307
Subject(s) - exponential function , simple (philosophy) , basis set , wave function , atomic orbital , basis (linear algebra) , hartree–fock method , projection (relational algebra) , sequence (biology) , set (abstract data type) , computational chemistry , mathematics , chemistry , atomic physics , statistical physics , physics , mathematical analysis , quantum mechanics , algorithm , molecule , geometry , computer science , electron , philosophy , biochemistry , epistemology , programming language
Hartree‐Fock wave functions for the He and Be isoelectronic sequences of ions are calculated using orbitals which are linear combinations of simple exponential functions. By a full optimization of the exponents and coefficients close approximations to the HartreeFock energies were obtained. To the same order of accuracy the resulting Hartree–Fock orbitals require fewer basis functions than used previously. A number of difficulties which arise in the numerical procedures as the size of the basis set is increased are analysed in detail. Similar results are obtained for the Li sequence using the Unrestricted HartreeFock method with and without projection.