On approximate projection models

Thompson, Lee M.; Hratchian, Hrant P.

doi:10.1080/00268976.2018.1554828

Cited by 19 publications

(36 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…75,76 In fact, several works have shown the effectiveness of this model and demonstrated the condition for which this model is suitable. 64,65,77,78 To carry out AP calculations, two converged determinants are required: (…”

Section: Approximate Projection Methodsmentioning

confidence: 99%

Good Vibrations: Calculating Excited State Frequencies Using Ground State Self-Consistent Field Models

Taka

Corzo

Pribram‐Jones

et al. 2021

Preprint

View full text Add to dashboard Cite

△SCF methods have proven to be reliable computational tools for the assignment and interpretation of photoelectron spectra of isolated molecules. These results have increased the interest in △SCF techniques for electronic excited states based on improved algorithms that prevent convergence to ground states. In this work, one of these △SCF improved algorithms is studied to demonstrate its ability to explore the molecular properties for excited states. Results from △SCF calculations for a set of representative molecules are compared with results obtained using time-dependent density functional theory and single substitution configuration interaction method. For the △SCF calculations, the efficacy of a spin-purification technique is explored to remedy some of the spin-contamination presented in some of the SCF solutions. The obtained results suggest that the proposed projection-based SCF scheme, in many cases, alleviates the spin--contamination present in the SCF single determinants, and provides a computational alternative for the efficient exploration of the vibrational properties of excited states molecules.

show abstract

Section: Approximate Projection Methodsmentioning

confidence: 99%

Good Vibrations: Calculating Excited State Frequencies Using Ground State Self-Consistent Field Models

Taka

Corzo

Pribram‐Jones

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Indeed, recent work from our lab has demonstrated the conditions under which such approaches are rigorously equivalent and those cases for which such models are numerically equivalent. 11 AP calculations using self-consistent field based models, such as HF and DFT, require two converged determinants: (1) a spin-contaminated broken-symmetry state; and (2) a spin-pure high-spin state. Those two determinants are used to assemble an AP energy according to…”

Section: Computational Detailsmentioning

confidence: 99%

“…28 Calculations using the AP model employed local implementations of analytic first-and second-derivative programs. 11,26,27 The examination of J-coupling calculations used the test set reported by Peralta and Rudra. 29,30 Calculations have been carried out using five different functionals: B3LYP, 31,32 LC-ωPBE, 33,34 CAM-B3LYP, 35 B3PW91 36 and ωB97XD.…”

Section: Computational Detailsmentioning

confidence: 99%

“…15 However, in the case of HF theory (particularly when small basis sets are employed) PAV appears to provide a clean separation of correlation types, which may present a pathway for ongoing theory and methods developments. 11 However, in the case of DFT approaches, such a claim is somewhat more tenuous due to the more complicated nature of the S 2 operator and inclusion of some degree of static correlation in many commonly used density functionals; although, many popular functionals exhibit similar numerical behavior to HF in molecular systems experiencing spin contamination from symmetry breaking. 8,16 Approximate Projection (AP), a PAV method proposed by Yamaguchi and coworkers, 17 and other related spin-decontamination models by Malrieu and coworkers [18][19][20][21] have been successfully used in energy calculations of transition metal complexes and organic diradicals.…”

Section: Introductionmentioning

confidence: 99%

“…[8][9][10] Nevertheless, in certain cases symmetry breaking yields an improved treatment of static correlation at single-reference cost, though static and dynamic correlation can become poorly balanced in such cases. 11 To correct spin contamination error, spin projection methods can be used to remove the contaminating spin states from a broken-symmetry determinant. When projection is carried out after a spin-contaminated determinant is fully converged, this approach is referred to as projection-after-variation (PAV).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Assessing the Calculation of Exchange Coupling Constants and Spin Crossover Gaps Using the Approximate Projection Model to Improve Density Functional Calculations

Sheng¹,

Thompson²,

Hratchian

2019

Preprint

View full text Add to dashboard Cite

This work evaluates the quality of exchange coupling constant and spin crossover gap calculations using density functional theory corrected by the Approximate Projection model. Results show that improvements using the Approximate Projection model range from modest to significant. This study demonstrates that, at least for the class of systems examined here, spin-projection generally improves the quality of density functional theory calculations of $J$-coupling constants and spin crossover gaps. Furthermore, it is shown that spin-projection can be important for both geometry optimization and energy evaluations. The Approximate Projection model provides an affordable and practical approach for effectively correcting spin-contamination errors in such calculations.

show abstract

Density-functional theory for electronic excited states

Herbert¹

2023

Theoretical and Computational Photochemistry

View full text Add to dashboard Cite

On approximate projection models

Cited by 19 publications

References 60 publications

Good Vibrations: Calculating Excited State Frequencies Using Ground State Self-Consistent Field Models

Good Vibrations: Calculating Excited State Frequencies Using Ground State Self-Consistent Field Models

Assessing the Calculation of Exchange Coupling Constants and Spin Crossover Gaps Using the Approximate Projection Model to Improve Density Functional Calculations

Density-functional theory for electronic excited states

Contact Info

Product

Resources

About