English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

A strategy is presented for variational orbital optimization intime-independent calculations of excited electronic states. The approachinvolves minimizing the energy while constraining specific degrees of freedomcorresponding to negative curvature on the electronic energy surface, followedby a fully unconstrained saddle point search. Both steps of thisfreeze-and-release strategy are carried out via direct orbital optimization atsimilar cost as ground state calculations. The approach is applied in orbitaloptimized density functional calculations of intramolecular charge transferexcited states where the maximum overlap method proves unable to preventvariational collapse to unphysical, charge delocalized solutions. Calculationswith the local density approximation and generalized gradient approximationfunctionals are carried out for a large set of charge transfer excitations inorganic molecules and the results compared to linear-response adiabatictime-dependent density functional theory (TD-DFT) calculations. Thetime-independent approach is fully variational and provides a relaxed excitedstate electron density that can be used to quantify the extent of chargetransfer. The TD-DFT calculations are found to generally overestimate thecharge transfer distance, even when including first-order orbital relaxationeffects with the Z-vector method in the so-called ''relaxed'' TD-DFT excitedstate density. Furthermore, while the error on the excitation energy relativeto theoretical best estimates is found to increase with the extent of chargetransfer for TD-DFT, no correlation is observed for the orbital optimizedcalculations, leading to a significant improvement for the excitations withstrong charge transfer character.

Orbital optimized vs time-dependent density functional calculations of intramolecular charge transfer excited states