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Kohn–Sham studies of oxygen systems
Author(s) -
Politzer Peter,
Lane Pat
Publication year - 2000
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/(sici)1097-461x(2000)77:1<336::aid-qua32>3.0.co;2-u
Subject(s) - maxima and minima , bracketing (phenomenology) , thermodynamics , work (physics) , standard enthalpy of formation , basis (linear algebra) , basis set , value (mathematics) , chemistry , density functional theory , physics , computational chemistry , theoretical physics , mathematics , mathematical analysis , philosophy , statistics , epistemology , geometry
The objective of this work was to use Kohn–Sham density functional methods to compute the enthalpies of formation of O 4 , O 6 , O 8 , and O 12 . To ascertain the most effective functional combinations and basis sets for this purpose, a variety of these were first tested by computing the energetics of a group of O 2 and O 3 reactions for which the relevant experimental data are available. On the basis of these results, the BLYP and BPW91 functionals were selected, in conjunction with the 6‐31G* and 6‐311G(2df) basis sets. The calculated enthalpies of formation of O 4 varied between 92.6 and 97.2 kcal/mol, bracketing a reported CCSD(T) value of 95 kcal/mol. For O 6 , O 8 , and O 12 , however, Kohn–Sham procedures were unable to consistently locate energy minima, even though Hartree–Fock and MP2 approaches do succeed in this respect. It appears that any energy minima that may in reality exist for O 6 , O 8 , and O 12 are very shallow, which is consistent with a conclusion reached earlier for O 4 . © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 336–340, 2000