Extended Geminal Models

Røeggen, I.

doi:10.1007/3-540-48972-x_5

Cited by 15 publications

(12 citation statements)

References 44 publications

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“…One of the improvements of this version of the EXRHF model compared with the one described in [9] is related to the single-pair correction terms {⑀ K }. In the present work, they are determined by a twostep iterative procedure.…”

Section: Exrhf Modelsmentioning

confidence: 99%

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Interatomic potential for the X¹Σ state of Be₂, revisited

Røeggen

Veseth

2004

Int J of Quantum Chemistry

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Section: Exrhf Modelsmentioning

confidence: 99%

“…The EXGEM model adopted in this work is an improved version of a model described in a recent review [9]. In this section, we describe the essential elements of the model, to make our work easily accessible.…”

Section: Theoretical Frameworkmentioning

confidence: 99%

Interatomic potential for the X¹Σ state of Be₂, revisited

Røeggen

Veseth

2004

Int J of Quantum Chemistry

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“…A key element in this computational scheme is the introduction of UHF geminals. Our approach has strong similarity to the extended geminal models introduced by Røeggen 22,26 and the form of the incremental scheme advocated by Stoll and co-workers [23][24][25] for closed shell systems. The more recent work by Bytautas and Ruedenberg 30 is also relevant in this context.…”

Section: Numerical Modelsmentioning

confidence: 69%

“…Third, the energy incremental scheme. [21][22][23][24][25][26] The total energy is written as a sum of intra-atomic terms, diatomic terms, and so on. At the highest level, the model is equivalent to a full configuration interaction (FCI) model.…”

Section: The Patmos Modelmentioning

confidence: 99%

Perturbed atoms in molecules and solids: The PATMOS model

Røeggen

Gao

2013

The Journal of Chemical Physics

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A new computational method for electronic-structure studies of molecules and solids is presented. The key element in the new model -denoted the perturbed atoms in molecules and solids model -is the concept of a perturbed atom in a complex. The basic approximation of the new model is unrestricted Hartree Fock (UHF). The UHF orbitals are localized by the Edmiston-Ruedenberg procedure. The perturbed atoms are defined by distributing the orbitals among the nuclei in such a way that the sum of the intra-atomic UHF energies has a minimum. Energy corrections with respect to the UHF energy, are calculated within the energy incremental scheme. The most important threeand four-electron corrections are selected by introducing a modified geminal approach. Test calculations are performed on N 2 , Li 2 , and parallel arrays of hydrogen atoms. The character of the perturbed atoms is illustrated by calculations on H 2 , CH 4 , and C 6 H 6 .

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“…The present renaissance of geminal theories [29][30][31][32][33][34][35][36][37][38][39][40][41][42] is perhaps a consequence of the need of simple but flexible and qualitatively correct reference states in multi-configuration theory.…”

Section: Introductionmentioning

confidence: 99%