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An improved algorithm for the normalized elimination of the small-component method

Zou, W., Filatov, M. & Cremer, D., Dec-2011, In : Theoretical Chemistry Accounts. 130, 4-6, p. 633-644 12 p.

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DOI

  • Wenli Zou
  • Michael Filatov
  • Dieter Cremer

A new algorithm for the iterative solution of the normalized elimination of the small component (NESC) method is presented that is less costly than previous algorithms and that is based on (1) solving the NESC equations for the uncontracted rather than contracted basis ("First-Diagonalize-then-Contract"), (2) a new iterative procedure for obtaining the NESC Hamiltonian ("iterative TU algorithm"), (3) the renormalization scheme connected to the picture change, and (4) a finite nucleus model with a Gaussian charge distribution. The accuracy of NESC energies, which match those of 4-component Dirac calculations, is demonstrated. Test calculations with CCSD(T), DFT, and large basis sets including high angular momentum basis functions (f,g,h,i) are presented to prove the general applicability of the new NESC algorithm. Comparison with other algorithms of solving the NESC equations are shortly discussed and time savings are presented.

Original languageEnglish
Pages (from-to)633-644
Number of pages12
JournalTheoretical Chemistry Accounts
Volume130
Issue number4-6
Publication statusPublished - Dec-2011

    Keywords

  • Normalized Elimination of the Small Component (NESC), Exact quasi-relativistic methods, Picture change, Finite nucleus model, DOUGLAS-KROLL TRANSFORMATION, RELATIVISTIC QUANTUM-CHEMISTRY, ORDER REGULAR APPROXIMATION, NONRELATIVISTIC METHODS, 2-COMPONENT HAMILTONIANS, PROJECTION OPERATORS, KINETIC BALANCE, DIRAC-EQUATION, BASIS SET, ELECTRON

ID: 5448388