Quantum renormalization groups based on natural orbitals

Abstract An Approximation of Löwdin's Natural Orbitals for Molecules with a Green's Function Method The many-body-pertubation theorie of the single-particle Green's function is used to get an approximate first-order density matrix. Slightly modified SCF-orbitals form the basis for the expansion. The mass-operator in Dyson's equation is considered up to second order in the Perturbation. In the present form the method is only applicable to ground states with closed shells. The ground states of the molecules LiH and NH3 serve as examples to demonstrate the usefulness of the directly calculated natural orbitals for application in the C I-method. The natural orbitals give a much better convergence of the C I-expansion than the SCF-orbitals do.

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Contracted basis sets for electrical property calculations derived from Second-order Møller-Plesset theory atomic natural orbitals

Theoretical Chemistry Accounts ◽

10.1007/s002140000149 ◽

2000 ◽

Vol 104 (5) ◽

pp. 385-391

Author(s):

Anthony J. Russell ◽

Mark A. Spackman

Keyword(s):

Electrical Property ◽

Second Order ◽

Basis Sets ◽

Natural Orbitals ◽

Atomic Natural Orbitals ◽

Moller Plesset

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Properties and Uses of Natural Orbitals

Reviews of Modern Physics ◽

10.1103/revmodphys.44.451 ◽

1972 ◽

Vol 44 (3) ◽

pp. 451-464 ◽

Cited By ~ 164

Author(s):

ERNEST R. DAVIDSON

Keyword(s):

Natural Orbitals

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NATURAL ORBITALS AND ELECTRON ELASTIC MAGNETIC SCATTERING BY NUCLEI

International Journal of Modern Physics E ◽

10.1142/s0218301396000396 ◽

1996 ◽

Vol 05 (04) ◽

pp. 717-724 ◽

Cited By ~ 4

Author(s):

D.N. KADREV ◽

A.N. ANTONOV ◽

M.V. STOITSOV ◽

S.S. DIMITROVA

Keyword(s):

Density Fluctuation ◽

Form Factors ◽

Wave Functions ◽

Magnetic Scattering ◽

Correlation Effects ◽

Valence Nucleon ◽

Nucleon System ◽

Natural Orbitals ◽

Transverse Form Factor ◽

Fluctuation Model

Natural orbitals obtained within the coherent density fluctuation model and containing nucleon correlation effects are used to calculate characteristics of the A-nucleon system, such as the electron elastic magnetic scattering form factors. The calculations are performed for nuclei with a doubly-closed core and a valence nucleon in a stretched configuration (j=l+1/2), such as the 17 O and 41 Ca nuclei. It is shown that the calculations of the transverse form factor using natural orbitals improve the agreement with the experimental data in comparison with the case when shell-model single-particle wave functions are used.

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