Reference spaces for multireference coupled-cluster theory: the challenge of the CoH molecule
| Autor: | Matheus Morato F. de Moraes, Yuri Alexandre Aoto |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Physics
Imagination Work (thermodynamics) Valence (chemistry) 010304 chemical physics media_common.quotation_subject Multireference configuration interaction 010402 general chemistry 01 natural sciences Potential energy Molecular physics 0104 chemical sciences Coupled cluster Atomic orbital 0103 physical sciences Molecule Physical and Theoretical Chemistry media_common |
| Zdroj: | Theoretical Chemistry Accounts. 139 |
| ISSN: | 1432-2234 1432-881X |
| DOI: | 10.1007/s00214-020-2584-1 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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