Picture change error in quasirelativistic electron/spin density, Laplacian and bond critical points

Bučinský, Lukáš; Kucková, Lenka; Malček, Michal; Kožı́šek, Jozef; Biskupič, Stanislav; Jayatilaka, Dylan; Büchel, Gabriel E.; Arion, Vladimir B.

doi:10.1016/j.chemphys.2014.04.013

Cited by 15 publications

(26 citation statements)

References 85 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…− complex is of no real influence [80]. Although the DKH2 approach does not completely decouple the large and small component of the Dirac Hamiltonian, while IOTC and/or X2C methods do [68,81,82,83,33], it has been shown that for the Cu atom the electron and spin densities as well as spin contamination at DKH2 and IOTC UHF levels of theory agree well with each other [79,80].…”

Section: Computational Detailsmentioning

confidence: 90%

“…Although the DKH2 approach does not completely decouple the large and small component of the Dirac Hamiltonian, while IOTC and/or X2C methods do [68,81,82,83,33], it has been shown that for the Cu atom the electron and spin densities as well as spin contamination at DKH2 and IOTC UHF levels of theory agree well with each other [79,80]. This has been further confirmed by the IOTC vs. DKH2 difference electron and spin density plots of the [OsCl 5 (Hpz)] − complex [80]. Therefore the DKH2 Hamiltonian has been used as the default within this study without the loss of generality.…”

Section: Computational Detailsmentioning

confidence: 99%

See 1 more Smart Citation

Spin contamination analogy, Kramers pairs symmetry and spin density representations at the 2-component unrestricted Hartree–Fock level of theory

Bučinský

Malček

Biskupič

et al. 2015

Computational and Theoretical Chemistry

Self Cite

View full text Add to dashboard Cite

Abstract"Kramers pairs symmetry breaking" is evaluated at the 2-component (2c) Kramers unrestricted and/or general complex Hartree-Fock (GCHF) level of theory, and its analogy with "spin contamination" at the 1-component (1c) unrestricted Hartree-Fock (UHF) level of theory is emphasized. The GCHF "Kramers pairs symmetry breaking" evaluation is using the square of overlaps between the set of occupied spinorbitals with the projected set of Kramers pairs. In the same fashion, overlaps between α and β orbitals are used in the evaluation of "spin contamination" at the UHF level of theory. In this manner, UHFŜ 2 expectation value is made formally extended to the GCHF case. The directly evaluated GCHF expectation value of theŜ 2 operator is considered for completeness. It is found that the 2c GCHF Kramers pairs symmetry breaking has a very similar extent in comparison to the 1c UHF spin contamination. Thus higher excited states contributions to the 1c so 2c unrestricted wave functions of open shell systems have almost the same extent and physical consequences. Moreover, it is formally shown that a single determinant wave function in the restricted open shell Kramers case has the expectation value ofK 2 operator equal to the negative number of open shell electrons, while the eigenvalue ofK 2 for the series of simple systems (H, He, He*-triplet, Li and Li*-quartet) are found to be equal to minus the square of the number of open shell electrons. The concept of unpaired electron density is extended to the GCHF regime and compared to UHF and restricted open shell Hartree-Fock spin density. The "collinear" and "noncollinear" analogs of spin density at the GCHF level of theory are considered as well. Spin contamination and/or Kramers pairs symmetry breaking, spin

show abstract

Section: Computational Detailsmentioning

confidence: 90%

Section: Computational Detailsmentioning

confidence: 99%

Spin contamination analogy, Kramers pairs symmetry and spin density representations at the 2-component unrestricted Hartree–Fock level of theory

Bučinský

Malček

Biskupič

et al. 2015

Computational and Theoretical Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…In this respect Komorovsky shows how the many fermions

\overset{K}{true}

operator and the pseudo Kramers operator

\hat{K}'

are related to each other, including explicit arguments on properties and behavior of

\hat{K}'^{2}

eigenvalues. Moreover, it has already been shown how the proper

\hat{K}'^{2}

eigenfunctions do look like, not only for the single reference pseudo Kramers cases (hydrogen, helium, and lithium atoms), but also for the “high spin”

| M_{k} | = N_{o}

He* (triplet) and Li* (quartet) cases with eigenfunctions of multireference character . Note that in the Kramers restricted open regime, the expectation value of the pseudo Kramers operator is equal to ‐ N 0 for a single reference wavefunction, showing on the relevance of pseudo Kramers operator with respect to the 2‐component electronic structure.…”

Section: Introductionmentioning

confidence: 93%

“…As in the case of nonrelativistic calculations one can exploit or not Kramers and/or time‐reversal symmetry in the 2c/4c calculations. It is of no real surprise that the analog of spin contamination of a single reference unrestricted wave function can be detected also at the Kramers unrestricted level of theory and can be assigned to the extent of higher excitation rank determinants in the Kramers unrestricted wave function . This has been achieved by means of enforcing additivity within Kramers (time‐reversal) symmetry.…”

Section: Introductionmentioning

confidence: 99%

“…This has been achieved by means of enforcing additivity within Kramers (time‐reversal) symmetry. In this respect, it was suggested to directly construct a many electron pseudo Kramers operator (

\hat{K}'

), which reflects the many electron spin operator in ansatz. Such an approach, herein referred to as pseudo Kramers operator, makes it possible to define the Kramers adapted eigenfunctions (

Ψ'

) of the

\hat{K}'^{2}

operator with the eigenvalue equal to

- M_{k}^{2}

.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Additivity in kramers pairs symmetry: Multiplets with up to four unpaired electrons

Bučinský

Malček

Biskupič

2016

Int. J. Quantum Chem.

Self Cite

View full text Add to dashboard Cite

Molecular QTAIM Topology Is Sensitive to Relativistic Corrections

Anderson

Rodríguez

Ayers

et al. 2019

Chemistry A European J

View full text Add to dashboard Cite

The topology of the molecular electron density of benzene dithiol gold cluster complex Au4−S−C6H4−S′−Au′4 changed when relativistic corrections were made and the structure was close to a minimum of the Born–Oppenheimer energy surface. Specifically, new bond paths between hydrogen atoms on the benzene ring and gold atoms appeared, indicating that there is a favorable interaction between these atoms at the relativistic level. This is consistent with the observation that gold becomes a better electron acceptor when relativistic corrections are applied. In addition to relativistic effects, here, we establish the sensitivity of molecular topology to basis sets and convergence thresholds for geometry optimization.

show abstract

Picture change error in quasirelativistic electron/spin density, Laplacian and bond critical points

Cited by 15 publications

References 85 publications

Spin contamination analogy, Kramers pairs symmetry and spin density representations at the 2-component unrestricted Hartree–Fock level of theory

Spin contamination analogy, Kramers pairs symmetry and spin density representations at the 2-component unrestricted Hartree–Fock level of theory

Additivity in kramers pairs symmetry: Multiplets with up to four unpaired electrons

Molecular QTAIM Topology Is Sensitive to Relativistic Corrections

Contact Info

Product

Resources

About