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We model Auger spectra using second-order Møller-Plesset perturbation (MP2) theory combined with complex-scaled basis functions. For this purpose, we decompose the complex MP2 energy of the core-hole state into contributions from specific decay channels and propose a corresponding equation-of-motion (EOM) method for computing the doubly ionized final states of Auger decay. These methods lead to significant savings in computational cost compared to our recently developed approaches based on coupled-cluster theory [F. Matz and T.-C. Jagau, J. Chem. Phys. 156, 114117 (2022)]. The test set for this study comprises water, ammonia, methane, hydrogen sulfide, phosphine, and silane. The energies of the final states of Auger decay are obtained with an accuracy comparable to EOM coupled-cluster singles and doubles (CCSD) theory. Partial decay widths and branching ratios between KLL, KLM, and KMM decay of K-shell holes in third-row hydrides are in good agreement with EOM-CCSD, while deviations are more significant for second-row hydrides. For L1-shell holes, which undergo Coster-Kronig decay, MP2 yields unphysical results. However, we show that a suitable shift of the MP2 energy denominators leads to more reliable branching ratios and spectra for these problematic cases.
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http://dx.doi.org/10.1063/5.0279034 | DOI Listing |
J Chem Phys
September 2025
Department of Chemistry, KU Leuven, B-3001 Leuven, Belgium.
We model Auger spectra using second-order Møller-Plesset perturbation (MP2) theory combined with complex-scaled basis functions. For this purpose, we decompose the complex MP2 energy of the core-hole state into contributions from specific decay channels and propose a corresponding equation-of-motion (EOM) method for computing the doubly ionized final states of Auger decay. These methods lead to significant savings in computational cost compared to our recently developed approaches based on coupled-cluster theory [F.
View Article and Find Full Text PDFACS Omega
September 2025
Departamento de Física y Química Teórica, Facultad de Química, Universidad Nacional Autónoma de México, Cd. Universitaria, 04510 Ciudad de Mexico, Mexico.
In this study, we introduce a set of novel computational strategies based on second-order Mo̷ller-Plesset perturbation theory (MP2), enhanced through acceleration techniques, such as the resolution of the identity (RI). These approaches are further refined via spin-component scaling (SCS), following Grimme's methodology, and are specifically calibrated for the quantitatively accurate prediction of weak interaction energiesinteractions that play a critical role in biological systems. Among the developed methods, three variants exhibit outstanding performance, surpassing the accuracy of several state-of-the-art, nondynamical electronic structure techniques.
View Article and Find Full Text PDFJ Chem Theory Comput
August 2025
State Key Laboratory of Precision and Intelligent Chemistry, and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
The second-order Møller-Plesset perturbation (MP2) theory is a post-Hartree-Fock method widely used to describe weak correlation energies in solids and molecules, but its high computational cost scales as (). Herein, we present an accurate and efficient implementation of MP2 within the plane-wave (PW) basis set for both periodic and molecular systems, which incorporates the interpolative separable density fitting (ISDF) decomposition and the Laplace transformation (LT) of the energy denominator. These innovations avoid the direct construction of electron repulsion integrals (ERIs) and reduce the computational complexity of MP2 from () to ().
View Article and Find Full Text PDFJ Phys Chem B
August 2025
Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States.
Developing accurate force fields for biomolecules remains a significant challenge due to the subtle energetic differences between various conformational states. We present a novel force field model for polyalanine, ALAMP2_25, developed using adaptive force matching (AFM) with Møller-Plesset perturbation theory at the second order (MP2) as the reference method. By fitting smaller model compounds and transferring parameters to larger peptides, we overcome the limitations of traditional AFM approaches and enable the use of more accurate electronic structure methods.
View Article and Find Full Text PDFJ Phys Chem A
September 2025
Department of Computer Science and the Institute of Technology, Resource and Energy-Efficient Engineering (TREE), University of Applied Sciences Bonn-Rhein-Sieg, Grantham-Allee 20, Sankt Augustin 53757, Germany.
The benzene···methanol dimer is one of the simplest systems that manifests an O-H···π nonbonded interaction. This interaction can be found in numerous systems, ranging from small-molecule clusters to biological systems, for example, phenyl-containing ligands bound within a protein's binding pocket. Herein, four gas-phase configurations are examined using quantum mechanics, which have O-H···π, CH···π and Bz-H···O interactions.
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