Comparison of CEPA and CP-MET methods

Koch, S.; Kutzelnigg, Werner

doi:10.1007/bf00553396

Cited by 21 publications

(21 citation statements)

References 41 publications

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“…CCSD{tq} L is also very accurate around the equilibrium distance, and starts to deviate slightly with increasing the nuclear distance due to the absence of the coupling between

{\overset{T}{true}}_{1}^{ext} + {\overset{T}{true}}_{2}^{ext}

and

{\overset{t}{true}}_{3}^{ext} + {\overset{t}{true}}_{4}^{ext}

. For HF, CC{SDtq} L entirely linearizing the external clusters presses down the total energy around FCI as frequently observed in the coupled‐electron pair approximations (CEPA) for exclusion principle violating (EPV) diagrams. In contrast, the treatment of CuH is more difficult compared to HF, and the accuracy of CC{SDtq} L is deteriorated for CuH especially at a short distance.…”

Section: Resultsmentioning

confidence: 80%

Partially linearized external models to active‐space coupled‐cluster through connected hextuple excitations

Ten‐no

2018

J Comput Chem

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Partially linearized external models to active-space coupled-cluster through hextuple excitations, for example, CC{SDtqph} , CCSD{tqph} , and CCSD{tqph} are implemented and compared with the full active-space CCSDtqph. The computational scaling of CCSDtqph coincides with that for the standard coupled-cluster singles and doubles (CCSD), yet with a much large prefactor. The approximate schemes to linearize the external excitations higher than doubles are significantly cheaper than the full CCSDtqph model. These models are applied to investigate the bond dissociation energies of diatomic molecules (HF, F , CuH, and CuF), and the potential energy surfaces of the bond dissociation processes of HF, CuH, H O, and C H . Among the approximate models, CCSD{tqph} provides very accurate descriptions compared with CCSDtqph for all of the tested systems. © 2018 Wiley Periodicals, Inc.

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“…CCSD{tq} L is also very accurate around the equilibrium distance, and starts to deviate slightly with increasing the nuclear distance due to the absence of the coupling between

{\overset{T}{true}}_{1}^{ext} + {\overset{T}{true}}_{2}^{ext}

and

{\overset{t}{true}}_{3}^{ext} + {\overset{t}{true}}_{4}^{ext}

Section: Resultsmentioning

confidence: 80%

Partially linearized external models to active‐space coupled‐cluster through connected hextuple excitations

Ten‐no

2018

J Comput Chem

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“…In a computer project, performed on 3000 generated curves of 250 series of all homogeneous two-step models, it was found that, for a linear method, a 'Theorem of Common Kinetic Runs' may be applied [10]: A MCC is independent of the activation data of both steps of all such models; furthermore, it is even approximately independent of their signal parameters (e.g. enthalpies).…”

Section: Theorem Of Common Kinetic Runsmentioning

confidence: 99%

Experimentally available kinetic codes as a tool for promising data extraction in thermal analysis

Koch

1992

Journal of Thermal Analysis

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By the study of 3000 kinetic runs for all homogeneous two-step models under variation of activation and signal parameters, it has been stated that the generated Mechanistic Concentration Code ( = MCC) is the best vehicle for data extraction in Thermal Analysis. It summarises the rate-controlling steps and their molecularities, independently of their activation data and (to 80-90%) of their method-specific signal parameters. Hence, an optimum evaluation needs the internal (best-fitted) reference step, the initial concentration of a reference reactant, and equal weight of theoretical and experimental results, reached using the same algorithms. Thus, the MCC of any series measured in general allows for a reliable model determination via the distribution into all two-step models, using the tools of probability and decision theory. A transfer of the strategy to heterogeneous reactions is discussed.

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“…͑30͒ and ͑36͒ give the integro-differential equations of factorizable coupled pair ͑FCP͒ procedure. 36,46 R terms of the approximated equations discussed above, together with CEPA͑2͒-type formula 40,41 are summarized in Table I.…”

Section: ͑27͒mentioning

confidence: 99%

“…In this paper we extended the WO techniques and coupled pair equations derived by Jeziorski et al 36 to Ps compounds whose electronic part is N-electron closed shell, and performed test calculations for PsH. We solved the coupled pair equations iteratively using linearized coupled pair ͑LCP͒, CEPA͑2͒-type, 40,41 complete coupled pair ͑CCP͒ procedures, and independent pair approximation ͑IPA͒. LCP procedure was used only to estimate perturbation energies.…”

Section: Introductionmentioning

confidence: 99%

Application of pair correlation theory to positronium compounds

Saito

Sasaki

1995

The Journal of Chemical Physics

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Extension of weak orthogonality ͑WO͒ techniques developed by Szalewicz et al. and coupled pair equations derived by Jeziorski et al. to positronium compounds are presented. These methods enable us to calculate many-electronic positronium compounds with explicitly correlated functions. These methods were applied to positronium hydride ͑PsH͒ with Hylleraas-type functions ͑HTF's͒, and the total energies, the positron-electron two-photon annihilation rates, and the positronium binding energies were calculated. Extended coupled pair equations were solved by CEPA͑2͒-type, complete coupled pair ͑CCP͒ procedures, and independent pair approximation ͑IPA͒ of CCP. For the total energies, IPA, CEPA͑2͒, and CCP procedures gave Ϫ0.78899, Ϫ0.78238, and Ϫ0.77471 au, respectively. For the two-photon annihilation rates, the respective procedure gave 2.088, 2.064, and 1.972 ns Ϫ1 , respectively.

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Comparison of CEPA and CP-MET methods

Cited by 21 publications

References 41 publications

Partially linearized external models to active‐space coupled‐cluster through connected hextuple excitations

Partially linearized external models to active‐space coupled‐cluster through connected hextuple excitations

Experimentally available kinetic codes as a tool for promising data extraction in thermal analysis

Application of pair correlation theory to positronium compounds

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