Density Functional Theory!. Hohenberg-Kohn-Sham approach turns an intractable N-body problem into N coupled one-body problems. This is tractable!. QM exchange-correlation effects in. This is the great unknown in DFT – we must approximate. Commonly used approximations: LDA, GGA, BLYP, B3LYP. Density Functional Theory. DFT is exact and should give agreement with experiment or high-level ab initio calculations in all situations. Approximate functionals perform well in many systems but can fail dramatically in other situations. This can be traced back to errors of DFA (density functional approximation).
Download PDFAbstract: The accurate description of open-shell molecules, in particular of transitionmetal complexes and clusters, is still an important challenge for quantumchemistry. While density-functional theory (DFT) is widely applied in thisarea, the sometimes severe limitations of its currently available approximaterealizations often preclude its application as a predictive theory. Here, wereview the foundations of DFT applied to open-shell systems, both within thenonrelativistic and the relativistic framework. In particular, we provide anin-depth discussion of the exact theory, with a focus on the role of the spindensity and possibilities for targeting specific spin states. It turns out thatdifferent options exist for setting up Kohn-Sham DFT schemes for open-shellsystems, which imply different definitions of the exchange-correlation energyfunctional and lead to different exact conditions on this functional. Finally,we suggest some possible directions for future developments.
What Is Exchange Correlation Functional
Submission history
From: Christoph R. Jacob [view email]
Exchange Correlation Functional In Dft
[v1] Mon, 11 Jun 2012 14:44:53 UTC (1,008 KB)
[v2]
Thu, 25 Oct 2012 09:26:48 UTC (1,090 KB)Full-text links:
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