Density delocalization in DFT

Approximate DFT is well-known to suffer from self-interaction error, which is expected to particularly plague the localized 3d and 4f electrons of transition metal complexes. In order to diagnose SIE, energetic delocalization error, i.e. deviation from piecewise linearity, is frequently used, but errors in the density are less well-understood. We carried out a systematic study to identify how diverse electronic structure methods for approximate SIE correction- DFT+U widely employed in the solid state versus global and range-separated hybrid tuning methods - localize the electron density in transition metal complexes. Interestingly, regardless of method employed or molecule studied, we showed that electron density is consistently localized away from the metal center and onto ligands, in sharp contrast to what people typically assume about SIE corrections in transition metal complexes. Additionally, we identified that recovery of piecewise linearity generally overestimated the necessary density correction with respect to accurate WFT references for weak field ligands and undercorrected the density for strong field ligands. These observations suggest that energetic and density errors should be separately addressed when improving density functionals for catalysis and materials design.

Check out our Article ASAP on this work here!

About Us

The Kulik group focuses on the development and application of new electronic structure methods and atomistic simulations tools in the broad area of catalysis.

Our Interests

We are interested in transition metal chemistry, with applications from biological systems (i.e. enzymes) to nonbiological applications in surface science and molecular catalysis.

Our Focus

A key focus of our group is to understand mechanistic features of complex catalysts and to facilitate and develop tools for computationally driven design.

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