Relativistic EOM-CCSD for Core-Excited and Core-Ionized State Energies Based on the Four-Component Dirac-Coulomb(-Gaunt) Hamiltonian
| Autor: | Marta L. Vidal, Loïc Halbert, Sonia Coriani, André Severo Pereira Gomes, Avijit Shee |
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| Rok vydání: | 2021 |
| Předmět: |
Hamiltonians
Binding energy chemistry.chemical_element 7. Clean energy 01 natural sciences Chemical calculations symbols.namesake Ionization 0103 physical sciences Coulomb Physical and Theoretical Chemistry Astatine Approximation Physics Energy 010304 chemical physics 3. Good health Computer Science Applications chemistry Excited state Halogen symbols Basis sets Ionization energy Atomic physics Hamiltonian (quantum mechanics) |
| Zdroj: | Halbert, L, Vidal, M L, Shee, A, Coriani, S & Severo Pereira Gomes, A 2021, ' Relativistic EOM-CCSD for Core-Excited and Core-Ionized State Energies Based on the Four-Component Dirac-Coulomb(-Gaunt) Hamiltonian ', Journal of Chemical Theory and Computation, vol. 7, no. 6, pp. 3583-3598 . https://doi.org/10.1021/acs.jctc.0c01203 |
| ISSN: | 1549-9626 1549-9618 |
| Popis: | We report an implementation of the core-valence separation approach to the four-component relativistic Hamiltonian-based equation-of-motion coupled-cluster with singles and doubles theory (CVS-EOM-CCSD) for the calculation of relativistic core-ionization potentials and core-excitation energies. With this implementation, which is capable of exploiting double group symmetry, we investigate the effects of the different CVS-EOM-CCSD variants and the use of different Hamiltonians based on the exact two-component (X2C) framework on the energies of different core-ionized and -excited states in halogen- (CH3I, HX, and X-, X = Cl-At) and xenon-containing (Xe, XeF2) species. Our results show that the X2C molecular mean-field approach [Sikkema, J.; J. Chem. Phys. 2009, 131, 124116], based on four-component Dirac-Coulomb mean-field calculations (2DCM), is capable of providing core excitations and ionization energies that are nearly indistinguishable from the reference four-component energies for up to and including fifth-row elements. We observe that two-electron integrals over the small-component basis sets lead to non-negligible contributions to core binding energies for the K and L edges for atoms such as iodine or astatine and that the approach based on Dirac-Coulomb-Gaunt mean-field calculations (2DCGM) are significantly more accurate than X2C calculations for which screened two-electron spin-orbit interactions are included via atomic mean-field integrals. |
| Databáze: | OpenAIRE |
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