Reference spaces for multireference coupled-cluster theory: the challenge of the CoH molecule

Autor(es)

de Moraes, Matheus Morato F. ^[1] ; Aoto, Yuri Alexandre ^[1]

Afiliação do(s) autor(es)

^[1] Fed Univ ABC UFABC, Ctr Math Comp & Cognit, Ave Estados 5001, Santo Andre, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: THEORETICAL CHEMISTRY ACCOUNTS; v. 139, n. 4 MAR 27 2020.
• Citações Web of Science: 0

Resumo

In multireference calculations on transition metal compounds, large active spaces including a second set of d orbitals are often used. However, with the increase in the system size and the complexity of the method, such calculations quickly become impractical. In this work, we looked for an inner valence active space for atomic cobalt and its hydride that correctly describes the transition energies among states with distinct configurations. Potential energy curves for the CoH molecule were obtained using a fixed reference space, where the orbitals are optimised only for the isolated atoms, avoiding undesirable sudden variations of the active orbitals. The calculations made use of the multireference configuration interaction (MRCI) and coupled-cluster (MRCC) theories. The accuracy of these calculations is carefully analysed, and we show that MRCC results are accurate, although not all electronic states are quantitatively described at the MRCI level. We conclude that the use of the fixed reference space is a viable approach to reduce the computational cost when large active spaces are prohibitive. Finally, a careful comparison of the present results with experimental values is carried out. (AU)

• 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