ISSN:
0020-7608
Keywords:
relativistic quantum chemistry
;
relativistic connections to expectation valves
;
two/one-component methods in relativity
;
perturbation methods in relativity
;
Douglas-Kroll approximation
;
mass-velocity+Darwin approximation
;
Chemistry
;
Theoretical, Physical and Computational Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The effect of the so-called picture change on expectation values of one-electron operators in approximate two(one)-component relativistic theories is discussed. This effect is expected to be particularly large for operators which assume large values in the vicinity of heavy nuclei. The numerical results illustrating the picture change effect on electric field gradients at nuclei have been obtained in the spin-free Pauli and Douglas-Kroll approximations. It has been found that the picture change effect lowers the electric field gradient at I in HI by about 1 a.u. Very large picture change effect (-8 a.u.) has been calculated for HAt. It is concluded that in accurate calculations of expectation values of operators involving high inverse powers of the electron-nucleus distance the picture change, which accompanies the transformation of the Dirac (Dirac-Coulomb) equation to approximate two(one)-component relativistic Hamiltonians, must be taken into account. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 68: 159-174, 1998
Additional Material:
4 Tab.
Type of Medium:
Electronic Resource
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