Accurate prediction of K-edge excitation energies using state-specific self-consistent perturbation theory
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arXiv
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| Format: | Preprint |
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2026
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| _version_ | 1866908881924390912 |
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| author | Tran, Lan Nguyen |
| author_facet | Tran, Lan Nguyen |
| contents | We present the application of the recently developed one-body Møller--Plesset perturbation theory (OBMP2) to the prediction of K-edge excited states. OBMP2 is a self-consistent perturbation theory in which a canonical transformation followed by a cumulant approximation yields an effective one-body Hamiltonian. This resulting operator augments the standard Fock operator with a one-body correlation potential containing double-excitation MP2 amplitudes, allowing molecular orbitals and orbital energies to be optimized in the presence of correlation. This self-consistent framework mitigates convergence and accuracy issues often encountered in standard non-iterative MP2 for open-shell systems and bond-stretching regimes. In this work, we evaluate the performance of an OBMP2-based approach for the calculation of K-edge excitations. Utilizing benchmark test sets of both closed-shell and open-shell molecules, we demonstrate that our method outperforms established standard techniques, including $Δ$DFT, EOM-CCSD, and USTEOM-CCSD. Our findings establish the OBMP2-based $Δ$SCF protocol as a robust and accurate new computational method for the treatment of K-edge excited states. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2603_11893 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Accurate prediction of K-edge excitation energies using state-specific self-consistent perturbation theory Tran, Lan Nguyen Chemical Physics We present the application of the recently developed one-body Møller--Plesset perturbation theory (OBMP2) to the prediction of K-edge excited states. OBMP2 is a self-consistent perturbation theory in which a canonical transformation followed by a cumulant approximation yields an effective one-body Hamiltonian. This resulting operator augments the standard Fock operator with a one-body correlation potential containing double-excitation MP2 amplitudes, allowing molecular orbitals and orbital energies to be optimized in the presence of correlation. This self-consistent framework mitigates convergence and accuracy issues often encountered in standard non-iterative MP2 for open-shell systems and bond-stretching regimes. In this work, we evaluate the performance of an OBMP2-based approach for the calculation of K-edge excitations. Utilizing benchmark test sets of both closed-shell and open-shell molecules, we demonstrate that our method outperforms established standard techniques, including $Δ$DFT, EOM-CCSD, and USTEOM-CCSD. Our findings establish the OBMP2-based $Δ$SCF protocol as a robust and accurate new computational method for the treatment of K-edge excited states. |
| title | Accurate prediction of K-edge excitation energies using state-specific self-consistent perturbation theory |
| topic | Chemical Physics |
| url | https://arxiv.org/abs/2603.11893 |