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PW86–PW91 density functional calculation of vertical ionization potentials: Some implications for present‐day functionals
Author(s) -
Shapley Warwick A.,
Chong Delano P.
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 - 10.1002/1097-461x(2001)81:1<34::aid-qua7>3.0.co;2-8
Subject(s) - ionization , density functional theory , chemistry , atomic physics , ground state , basis (linear algebra) , absolute deviation , ionization energy , molecule , basis set , molecular physics , physics , computational chemistry , ion , geometry , mathematics , statistics , organic chemistry
A total of 181 vertical ionization potentials (VIPs) of 41 molecules were calculated by density functional theory (DFT) employing the Perdew–Wang 1986 (PW86) exchange and Perdew–Wang 1991 (PW91) correlation functionals and using the aug‐cc‐pV5Z basis and experimental ground‐state geometries. The overall average absolute deviation (AAD) from experiment was found to be 0.55 eV and only 0.31 eV for linear molecules but 0.86 eV for nonplanar molecules. A number of VIPs were in error by over 2 eV. In particular, DFT performed most poorly when ionization was from an orbital with highly varying density gradients (which arise from the orbital's shape or compactness or through its density being distributed over a number of atoms). Indications are that many or all present‐day functionals suffer from the same failings. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 81: 34–52, 2001