Estudo da aplicação de métodos de extrapolação ao limite CBS para estados excitados moleculares
Nenhuma Miniatura disponível
Data
2025-01-31
Autores
Silva, Kessia Claudino da
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal do Espírito Santo
Resumo
In this work high-level ab initio calculations were performed using multiconfigurational methods. The objective of the work is not to propose a new method for energy extrapolation to the complete basis set limit, but to verify if the methods found in the literature and calibrated for ground state systems can also be applied to molecular excited states. A total of 24 systems were considered, and all calculations were performed using the AVXZ basis set (X = D, T, Q, 5 and 6). The analysis of the order of magnitude of the results obtained for the excited states was carried out, and comparisons with the results available in the literature for the ground states were made. Through the use of the USTE protocol, a compatibility was noted between the RMSD obtained for the correlation and MRCI energies extrapolated for the molecular systems in their excited states, in relation to the RMSD found for these systems in their ground states. The HF-E protocol was used to determine the CASSCF energy extrapolated of the first excited state of the molecular systems and, in this case, greater differences in the order of magnitude were found of the RMSD that we calculated, compared to those found in the literature for systems in their ground states. Thus, our work suggests that the USTE method can be applied similarly to excited molecular systems. However, with the results obtained for the CASSCF energy, it was not possible to affirm that the HF-E protocol can be applied to excited molecular systems in a similar way to what was constructed for the ground state. In this case, we raise the possibility of making some adjustments in the computational calculations (which were presented throughout the discussion), and a potential need for protocol calibration for this type of application.
Descrição
Palavras-chave
Extrapolação ao limite CBS , Estados excitados , Métodos multiconfiguracionais , Extrapolation to the CBS limit , Excited states , Multiconfigurational
methods