Extraction of local spin-coupled states by second quantized operators

Nakatani, Kaho; Higashi, Masahiro; Sato, Hirofumi

doi:10.1063/5.0092834

Cited by 3 publications

(4 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This task requires the determination of the spin of the atoms resulting from the molecular dissociation, as well as their electronic populations. The expectation value of the spin-squared operator b S 2 D E , corresponding to a global N-electron system, is partitioned into one-and two-center components according to [34][35][36][37][38][39].…”

Section: Theoretical Backgroundmentioning

confidence: 99%

⟨{\overset{truê}{S}}^{2}⟩

, corresponding to a global

N

‐electron system, is partitioned into one‐ and two‐center components according to [34–39].

⟨{\overset{truê}{S}}^{2}⟩ = \underset{A}{false\sum} {(⟨⟩, {\overset{S}{true}}^{2})}_{A} + \underset{A \neq B}{false\sum} {(⟨⟩, {\overset{S}{true}}^{2})}_{italicAB}

where

A

B

\dots

mean the different atomic centers composing the molecular system.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…Another purpose of this work is to illuminate the spin features of all species involved in the stretching of internuclear distances until reaching atomic dissociation. We describe the spin of the molecular entities as well as the electronic populations and local spins of the atoms resulting from the dissociation processes [34][35][36][37][38][39]. The results found using these DOCI methodologies in selected diatomic and polyatomic systems have been compared with those arising from the FCI method, in order to be able to assess the reliability of the restricted and unrestricted treatments within both, wave function based and 2-RDM based schemes.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Studies of molecular dissociation by means of restricted and unrestricted treatments within the doubly occupied configuration interaction framework

Garcia

Oña

Torre

et al. 2023

Int J of Quantum Chemistry

View full text Add to dashboard Cite

This work studies the performance of doubly occupied configuration interaction treatments based on the determination of wave functions and on the direct variational evaluation of two‐electron reduced density matrices in both, restricted and unrestricted approaches. We describe potential energy curves and spin contamination curves predicted by these methods for N‐electron molecular systems in their electronic ground states, at internuclear distances lying in intervals from near equilibrium geometries to dissociation limits. The corresponding numerical determinations in terms of energies, expectation values of the N‐electron spin‐squared operator, local spins, and electronic populations of the dissociation products are compared with those provided by the full configuration interaction procedure. An analysis of these results allows us to assess the abilities of the restricted and unrestricted methodologies and to illuminate the advantages and shortcomings of each of these treatments.

show abstract

Section: Theoretical Backgroundmentioning

confidence: 99%

⟨{\overset{truê}{S}}^{2}⟩

, corresponding to a global

N

‐electron system, is partitioned into one‐ and two‐center components according to [34–39].

⟨{\overset{truê}{S}}^{2}⟩ = \underset{A}{false\sum} {(⟨⟩, {\overset{S}{true}}^{2})}_{A} + \underset{A \neq B}{false\sum} {(⟨⟩, {\overset{S}{true}}^{2})}_{italicAB}

where

A

B

\dots

mean the different atomic centers composing the molecular system.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Studies of molecular dissociation by means of restricted and unrestricted treatments within the doubly occupied configuration interaction framework

Garcia

Oña

Torre

et al. 2023

Int J of Quantum Chemistry

View full text Add to dashboard Cite

show abstract

“…We focused on these singlet and triplet components to characterize the formation and dissociation of chemical bonds. 47 The potential significance of the GP wave function might be positioned in several ways. As mentioned, the broken-symmetry approach in geminal-based methods is promising for correcting the inter-geminal correlation effect.…”

Section: Communicationmentioning

confidence: 99%

A geminal theory based on the generalized electron pairing

Nakatani

Sato

2023

J. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

As in the hierarchy of the Hartree-Fock theory in terms of spin symmetry, the extension of spin functions in a theory of two-electron units or geminal, was developed in this study. A trial wave function is constructed as an antisymmetrized product of geminals, in which singlet and triplet two-electron functions are fully mixed. We present a variational optimization method for this generalized pairing wave function in the strong orthogonality condition. The present method is considered an extension of the antisymmetrized product of strongly orthogonal geminals or perfect pairing generalized valence bond methods, maintaining the compactness of the trial wave function. The obtained brokensymmetry solutions were similar to the unrestricted Hartree-Fock wave functions in terms of spin contamination while giving lower energy due to the inclusion of the electron correlation effect in geminals. The degeneracy of the obtained broken-symmetry solutions in the Sz space is reported for the tested four-electron systems.

show abstract

The nature of the chemical bond

Gordon

Xantheas

2023

The Journal of Chemical Physics

View full text Add to dashboard Cite

Extraction of local spin-coupled states by second quantized operators

Cited by 3 publications

References 48 publications

Studies of molecular dissociation by means of restricted and unrestricted treatments within the doubly occupied configuration interaction framework

Studies of molecular dissociation by means of restricted and unrestricted treatments within the doubly occupied configuration interaction framework

A geminal theory based on the generalized electron pairing

The nature of the chemical bond

Contact Info

Product

Resources

About