Communication: Recovering the flat-plane condition in electronic structure theory at semi-local DFT cost
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1710.02378.pdf
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1.38 MB
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Author(s)
Bajaj, Akash
Janet, Jon Paul
Kulik, Heather Janine
Date Issued
November 2017
Journal
Journal of Chemical Physics
Publisher
AIP Publishing
Citation
Bajaj, Akash et al. “Communication: Recovering the Flat-Plane Condition in Electronic Structure Theory at Semi-Local DFT Cost.” The Journal of Chemical Physics 147, 19 (November 2017): 191101 © 2017 Author(s)
Version
Original manuscript
Abstract
The flat-plane condition is the union of two exact constraints in electronic structure theory: (i) energetic piecewise linearity with fractional electron removal or addition and (ii) invariant energetics with change in electron spin in a half filled orbital. Semi-local density functional theory (DFT) fails to recover the flat plane, exhibiting convex fractional charge errors (FCE) and concave fractional spin errors (FSE) that are related to delocalization and static correlation errors. We previously showed that DFT+U eliminates FCE but now demonstrate that, like other widely employed corrections (i.e., Hartree-Fock exchange), it worsens FSE. To find an alternative strategy, we examine the shape of semi-local DFT deviations from the exact flat plane and we find this shape to be remarkably consistent across ions and molecules. We introduce the judiciously modified DFT (jmDFT) approach, wherein corrections are constructed from few-parameter, low-order functional forms that fit the shape of semi-local DFT errors. We select one such physically intuitive form and incorporate it self-consistently to correct semi-local DFT. We demonstrate on model systems that jmDFT represents the first easy-to-implement, no-overhead approach to recovering the flat plane from semi-local DFT.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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DOI of Published Version
https://doi.org/10.1063/1.5008981
