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RESEARCH PRODUCT
Direct perturbation theory in terms of energy derivatives: scalar-relativistic treatment up to sixth order.
Jürgen GaussStella StopkowiczWerner SchwalbachLan Chengsubject
HydrogenChemistryComputationGeneral Physics and AstronomyPerturbation (astronomy)chemistry.chemical_elementMonotonic functionThird derivativeHydrofluoric AcidHydrobromic AcidDipoleRate of convergenceQuantum mechanicsQuantum electrodynamicsQuantum TheoryHydrochloric AcidPhysical and Theoretical ChemistryRelativistic quantum chemistrydescription
A formulation of sixth-order direct perturbation theory (DPT) to treat relativistic effects in quantum-chemical calculations is presented in the framework of derivative theory. Detailed expressions for DPT6 are given at the Hartree-Fock level in terms of the third derivative of the energy with respect to the relativistic perturbation parameter defined as λ(rel)=c(-2). They were implemented for the computation of scalar-relativistic energy corrections. The convergence of the scalar-relativistic DPT expansion is studied for energies and first-order properties such as dipole moment and electric-field gradient within the series of the hydrogen halides (HX, X = F, Cl, Br, I, and At). Comparison with spin-free Dirac-Coulomb calculations indicates that the DPT series exhibits a smooth and monotonic convergence. The rate of convergence, however, depends on the charge of the involved nuclei and significantly slows down for heavy-element compounds.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2011-11-21 | The Journal of chemical physics |