Paper

{
  "raw_xml": "<entry>\n    <id>http://arxiv.org/abs/2603.11893v1</id>\n    <title>Accurate prediction of K-edge excitation energies using state-specific self-consistent perturbation theory</title>\n    <updated>2026-03-12T13:06:00Z</updated>\n    <link href='https://arxiv.org/abs/2603.11893v1' rel='alternate' type='text/html'/>\n    <link href='https://arxiv.org/pdf/2603.11893v1' rel='related' title='pdf' type='application/pdf'/>\n    <summary>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.</summary>\n    <category scheme='http://arxiv.org/schemas/atom' term='physics.chem-ph'/>\n    <published>2026-03-12T13:06:00Z</published>\n    <arxiv:comment>7 pages, 3 figures, 2 tables</arxiv:comment>\n    <arxiv:primary_category term='physics.chem-ph'/>\n    <author>\n      <name>Lan Nguyen Tran</name>\n    </author>\n  </entry>"
}