Benchmark Calculations of K-Edge Ionization Energies for First-Row Elements Using Scalar-Relativistic Core–Valence-Separated Equation-of-Motion Coupled-Cluster Methods

Abstract

 Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

New and Efficient Equation-of-Motion Coupled-Cluster Framework for Core-Excited and Core-Ionized States

“…The reduced absolute shifts from experiments compared to the previously presented CVS-CCSD approach 28 are most likely due to effective error cancellation between the neglect of core correlation in the ground state, its inclusion in the excited states and the neglect of higher-order correlation and excitation effects in the (EOM-)CCSD method. Even if one can argue that triple and higher excitation effects (as well as relativistic effects) are required to attain fully quantitative agreement with experiment, 103,104 we believe that the results reported here give plenty of evidence that our ab initio approach is a useful addition to the toolbox of computational spectroscopy: it offers a robust, black-box, and reliable scheme for the interpretation of modern X-ray experiments, at a lower computational cost and more efficiently than the previously proposed CVS scheme, 28…”

Efficient calculations of a large number of highly excited states for multiconfigurational wavefunctions

“…Solutions using complex‐valued approaches exist but are associated with increased cost . Simply neglecting the continuum coupling altogether using CVS gives good results and is better than using a poor continuum description …”

A New and Efficient Equation-of-Motion Coupled-Cluster Framework for Core-Excited and Core-Ionized States

“…The reduced absolute shifts from experiments compared to the previously presented CVS-CCSD approach 28 are most likely due to effective error cancellation between the neglect of core correlation in the ground state, its inclusion in the excited states and the neglect of Theory and Computation 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 can argue that triple and higher excitation effects (as well as relativistic effects) are required to attain fully quantitative agreement with experiment, 103,104 we believe that the results reported here give plenty of evidence that our ab initio approach is a useful addition to the toolbox of computational spectroscopy: it offers a robust, black-box, and reliable scheme for the interpretation of modern X-ray experiments, at a lower computational cost and more efficiently than the previously proposed CVS scheme, 28…”