Finite-order method to calculate approximate density matrices in the Fock-space multireference coupled cluster theory

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Finite-order method to calculate approximate density matrices in the Fock-space multireference coupled cluster theory. / Oleynichenko, A.V.; Zaitsevskii, A.; Skripnikov, L.V.; Eliav, E.

In: Molecular Physics, 24.10.2024.

Research output: Contribution to journal › Article › peer-review

BibTeX

@article{c240280b13a04710a8a09abe7eb4bb6b,

title = "Finite-order method to calculate approximate density matrices in the Fock-space multireference coupled cluster theory",

abstract = "An efficient approach to calculate approximate pure-state and transition reduced density matrices in the framework of the multireference relativistic Fock-space coupled cluster (FS CC) theory is proposed. The method is based on the effective operator formalism and consists of the direct substitution of the FS CC Ansatz for a wave operator into the effective operator expression with the subsequent truncation of expansion at the terms quadratic in cluster amplitudes. The final density matrix is defined by active-space density matrices of different ranks {\textquoteleft}dressed{\textquoteright} with contributions from cluster operators. The method gives a connected expression for pure-state density matrices, provided that the intermediate normalisation condition is fulfilled. Moreover, under some additional assumptions, the connectivity can also be ensured for calculated transition property matrix elements and natural transition spinors. The developed technique allows for fast and accurate calculations of one-particle reduced density matrices for a wide range of electronic states. A pilot application of the new technique to construct averaged atomic natural orbital (ANO) basis sets for fully relativistic electronic structure calculations is presented. {\textcopyright} 2024 Informa UK Limited, trading as Taylor & Francis Group.",

keywords = "Approximation theory, Relativity, State space methods, Coupled-cluster theory, Density matrix, Effective operator, Finite order, Fock spaces, Multi reference, Pure state, Reduced-density matrix, Relativistics, States and transitions, Matrix algebra",

author = "A.V. Oleynichenko and A. Zaitsevskii and L.V. Skripnikov and E. Eliav",

note = "Export Date: 4 November 2024 CODEN: MOPHA",

year = "2024",

month = oct,

day = "24",

doi = "10.1080/00268976.2024.2413416",

language = "Английский",

journal = "Molecular Physics",

issn = "0026-8976",

publisher = "Taylor & Francis",

}

RIS

TY - JOUR

T1 - Finite-order method to calculate approximate density matrices in the Fock-space multireference coupled cluster theory

AU - Oleynichenko, A.V.

AU - Zaitsevskii, A.

AU - Skripnikov, L.V.

AU - Eliav, E.

N1 - Export Date: 4 November 2024 CODEN: MOPHA

PY - 2024/10/24

Y1 - 2024/10/24

N2 - An efficient approach to calculate approximate pure-state and transition reduced density matrices in the framework of the multireference relativistic Fock-space coupled cluster (FS CC) theory is proposed. The method is based on the effective operator formalism and consists of the direct substitution of the FS CC Ansatz for a wave operator into the effective operator expression with the subsequent truncation of expansion at the terms quadratic in cluster amplitudes. The final density matrix is defined by active-space density matrices of different ranks ‘dressed’ with contributions from cluster operators. The method gives a connected expression for pure-state density matrices, provided that the intermediate normalisation condition is fulfilled. Moreover, under some additional assumptions, the connectivity can also be ensured for calculated transition property matrix elements and natural transition spinors. The developed technique allows for fast and accurate calculations of one-particle reduced density matrices for a wide range of electronic states. A pilot application of the new technique to construct averaged atomic natural orbital (ANO) basis sets for fully relativistic electronic structure calculations is presented. © 2024 Informa UK Limited, trading as Taylor & Francis Group.

AB - An efficient approach to calculate approximate pure-state and transition reduced density matrices in the framework of the multireference relativistic Fock-space coupled cluster (FS CC) theory is proposed. The method is based on the effective operator formalism and consists of the direct substitution of the FS CC Ansatz for a wave operator into the effective operator expression with the subsequent truncation of expansion at the terms quadratic in cluster amplitudes. The final density matrix is defined by active-space density matrices of different ranks ‘dressed’ with contributions from cluster operators. The method gives a connected expression for pure-state density matrices, provided that the intermediate normalisation condition is fulfilled. Moreover, under some additional assumptions, the connectivity can also be ensured for calculated transition property matrix elements and natural transition spinors. The developed technique allows for fast and accurate calculations of one-particle reduced density matrices for a wide range of electronic states. A pilot application of the new technique to construct averaged atomic natural orbital (ANO) basis sets for fully relativistic electronic structure calculations is presented. © 2024 Informa UK Limited, trading as Taylor & Francis Group.

KW - Approximation theory

KW - Relativity

KW - State space methods

KW - Coupled-cluster theory

KW - Density matrix

KW - Effective operator

KW - Finite order

KW - Fock spaces

KW - Multi reference

KW - Pure state

KW - Reduced-density matrix

KW - Relativistics

KW - States and transitions

KW - Matrix algebra

UR - https://www.mendeley.com/catalogue/ece73839-42a1-36c2-b4da-fa7797d6bd05/

U2 - 10.1080/00268976.2024.2413416

DO - 10.1080/00268976.2024.2413416

M3 - статья

JO - Molecular Physics

JF - Molecular Physics

SN - 0026-8976

M1 - e2413416

ER -

ID: 126693916