1966
DOI: 10.1063/1.1727841
|View full text |Cite
|
Sign up to set email alerts
|

Pseudonatural Orbitals as a Basis for the Superposition of Configurations. I. He2+

Abstract: The use of pseudonatural orbitals (PNO) is proposed to improve the rate of convergence in the superposition of configurations (SOC). Natural orbitals are determined for selected electron pairs in the Hartree—Fock field of the n−2 electron core and are then used as the basis for the total SOC calculation. Since these natural orbitals are not natural for the n-electron system they are considered false or pseudonatural orbitals when used in the n-electron problem. The PNO basis has been applied to … Show more

Help me understand this report

Search citation statements

Order By: Relevance

Paper Sections

Select...
2
1

Citation Types

0
74
0

Year Published

1968
1968
2019
2019

Publication Types

Select...
9
1

Relationship

1
9

Authors

Journals

citations
Cited by 191 publications
(74 citation statements)
references
References 20 publications
0
74
0
Order By: Relevance
“…[15][16][17][18][19][20][21][22] Perhaps the most powerful method of doing so is to use frozen natural orbitals ͑FNOs͒. 18,20,[23][24][25][26][27][28] These orbitals use information from an approximate one-particle reduced density matrix to choose the best subset of one-particle orbitals within which to perform a correlated calculation. When using FNOs based on the MBPT͑2͒ density matrix, 29,30 this truncated orbital set has been shown to be surprisingly effective at truncating larger basis sets, allowing ϳ50% of a modified unoccupied orbital set to be removed without significant changes to ground state CC energies and density matrices.…”
Section: Introductionmentioning
confidence: 99%
“…[15][16][17][18][19][20][21][22] Perhaps the most powerful method of doing so is to use frozen natural orbitals ͑FNOs͒. 18,20,[23][24][25][26][27][28] These orbitals use information from an approximate one-particle reduced density matrix to choose the best subset of one-particle orbitals within which to perform a correlated calculation. When using FNOs based on the MBPT͑2͒ density matrix, 29,30 this truncated orbital set has been shown to be surprisingly effective at truncating larger basis sets, allowing ϳ50% of a modified unoccupied orbital set to be removed without significant changes to ground state CC energies and density matrices.…”
Section: Introductionmentioning
confidence: 99%
“…[26][27][28] NOs, often extracted from affordable MP2 computations, are also extremely useful in local correlation methods 29,30 , as exemplified by Pair Natural Orbitals (PNOs), 31,32 that tailor the virtual space to each electron pair, and that are extracted from the appropriate density matrix by SVD. PNOs were recently revisited with much success for accurate local correlation methods.…”
mentioning
confidence: 99%
“…The negative ion H ; state formed here is also ~elated to the lowest energy resonance state of H2 considered responsible for enhanced vibrational excitation at low incide nt electron energies [3]. Three electrons are now interpenetrating and the correlation [5] is similar to that in He~ and H3• However, there are offsetting H.F. and correlation errors that are s trongly de pe ndent on the geometry. The de pth of the H.F. attractive well should approximate the correlated one.…”
Section: Introductionmentioning
confidence: 89%