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Spurious fractional charge on dissociated atoms: Pervasive and resilient self-interaction error of common density functionals.
Spurious fractional charge on dissociated atoms: Pervasive and resilient self-interaction error of common density functionals.
- Source :
-
Journal of Chemical Physics . 11/21/2006, Vol. 125 Issue 19, p194112. 8p. 3 Charts, 5 Graphs. - Publication Year :
- 2006
-
Abstract
- Semilocal density functional approximations for the exchange-correlation energy can improperly dissociate a neutral molecule XY (Y≠X) to fractionally charged fragments X+q...Y-q with an energy significantly lower than X0...Y0. For example, NaCl can dissociate to Na+0.4...Cl-0.4. Generally, q is positive when the lowest-unoccupied orbital energy of atom Y0 lies below the highest-occupied orbital energy of atom X0. The first 24 open sp-shell atoms of the Periodic Table can form 276 distinct unlike pairs XY, and in the local spin density approximation 174 of these display fractional-charge dissociation. Finding these lowest-energy solutions with standard quantum chemistry codes, however, requires special care. Self-interaction-corrected (SIC) semilocal approximations are exact for one-electron systems and also reduce the spurious fractional charge q. The original SIC of Perdew and Zunger typically reduces q to 0. A scaled-down SIC with better equilibrium properties sometimes fails to reduce q all the way to 0. The desideratum of “many-electron self-interaction freedom” is introduced as a generalization of the one-electron concept. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00219606
- Volume :
- 125
- Issue :
- 19
- Database :
- Academic Search Index
- Journal :
- Journal of Chemical Physics
- Publication Type :
- Academic Journal
- Accession number :
- 23250139
- Full Text :
- https://doi.org/10.1063/1.2387954