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Multi-d-Occupancy as an Alternative Definition for the Double d-Shell Effect

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Autor(es):
de Moraes, Matheus Morato F. ; Aoto, Yuri Alexandre
Número total de Autores: 2
Tipo de documento: Artigo Científico
Fonte: Journal of Physical Chemistry A; v. 127, n. 48, p. 16-pg., 2023-11-20.
Resumo

Despite the prevalence of first-row transition metal-containing compounds in virtually all areas of chemistry, the accurate modeling of these systems is a known challenge for the theoretical chemistry community. Such a challenge is shown in a myriad of facets; among them are difficulties in defining ground-state multiplicities, disagreement in the results from methods considered highly accurate, and convergence problems in calculations for excited states. These problems cause a scarcity of reliable theoretical data for transition metal-containing systems. In this work, we explore the double d-shell effect that plagues and makes the application of multireference methods to this type of system difficult. We propose an alternative definition for this effect based on the mixing among d-occupancy configurations or the multi-d-occupancy character of the wave function. Moreover, we present a protocol able to include this effect in multireference calculations using an active space smaller than that usually used in the literature. A molybdenum-copper model system and its copper subsystem are used as example study cases, in particular, the molybdenum-copper charge transfer of the former and the electron affinity of the latter. We have shown that our alternative definition can be used to analyze their reference wave functions qualitatively. Based on this qualitative description, it is possible to optimize an active space without a second d-shell able to obtain relative energies accurately. Seeing the double d-shell effect through the lens of a multi-d-occupancy character, it is possible to correctly describe the wave function, improve the accuracy of the relative energies, and reduce the computational cost of multireference calculations. That way, we believe that this alternative definition has the potential to improve the modeling of first-row transition metal-containing compounds both for their ground and excited electronic structures. (AU)

Processo FAPESP: 21/09907-5 - Usando ferramentas da teoria quântica da informação para medir a qualidade de espaços ativos
Beneficiário:Matheus Morato Ferreira de Moraes
Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado Direto
Processo FAPESP: 17/21199-0 - As variedades diferenciáveis da teoria da estrutura eletrônica
Beneficiário:Yuri Alexandre Aoto
Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
Processo FAPESP: 18/14629-1 - Moléculas diatômicas contendo cobalto e seus estados excitados
Beneficiário:Matheus Morato Ferreira de Moraes
Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
Processo FAPESP: 18/04617-6 - As variedades diferenciáveis da teoria da estrutura eletrônica
Beneficiário:Yuri Alexandre Aoto
Modalidade de apoio: Bolsas no Brasil - Jovens Pesquisadores