Abstract
Based on selfconsistent field (SCF) atomic meanfield (amf) quantities, we present two simple yet computationally efficient and numerically accurate matrixalgebraic approaches to correct both scalarrelativistic and spin–orbit twoelectron picturechange effects (PCEs) arising within an exact twocomponent (X2C) Hamiltonian framework. Both approaches, dubbed amfX2C and e(xtended)amfX2C, allow us to uniquely tailor PCE corrections to meanfield models, viz. Hartree–Fock or Kohn–Sham DFT, in the latter case also avoiding the need for a pointwise calculation of exchange–correlation PCE corrections. We assess the numerical performance of these PCE correction models on spinor energies of group 18 (closedshell) and group 16 (openshell) diatomic molecules, achieving a consistent ≈10−5 Hartree accuracy compared to reference fourcomponent data. Additional tests include SCF calculations of molecular properties such as absolute contact density and contact density shifts in copernicium fluoride compounds (CnF𝑛, n = 2,4,6), as well as equationofmotion coupledcluster calculations of xray coreionization energies of 5𝑑 and 6𝑑containing molecules, where we observe an excellent agreement with reference data. To conclude, we are confident that our (e)amfX2C PCE correction models constitute a fundamental milestone toward a universal and reliable relativistic twocomponent quantumchemical approach, maintaining the accuracy of the parent fourcomponent one at a fraction of its computational cost.
Originalsprog  Engelsk 

Artikelnummer  114106 
Tidsskrift  The Journal of Chemical Physics 
Vol/bind  157 
Udgave nummer  11 
ISSN  00219606 
DOI  
Status  Udgivet  21. sep. 2022 
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Replication Data for: Exact twocomponent Hamiltonians for relativistic quantum chemistry: Twoelectron picturechange corrections made simple
Knecht, S. (Ophavsmand), Repisky, M. (Ophavsmand), Jensen, H. J. A. (Ophavsmand) & Saue, T. (Ophavsmand), Zenodo, 6. apr. 2022
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