Application of the Unified Singlet and Triplet Electron-Pair Extrapolation Scheme with Basis Set Rehierarchization to Tensorial Properties

Pansini, F.N.N.; Neto, A. Canal; Varandas, A. J. C.

doi:10.1021/jp512397n

Cited by 15 publications

(15 citation statements)

References 47 publications

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“…As noted elsewhere, any basis set used for polarizability calculations must be flexible enough to describe the external orbital distortions due to the applied electrical field . Augmented basis sets should therefore be best suited for response property calculations, with the results reported here reinforcing such a view.…”

Section: Other Propertiesmentioning

confidence: 57%

“…Table presents average polarizabilities extrapolated from the procedure proposed elsewhere, whereby the HF part is extrapolated via HF‐E protocol . Also given for comparison are raw CCSD(T) values and experimental results.…”

Section: Other Propertiesmentioning

confidence: 99%

“… Note : The CBS extrapolation is performed using a procedure reported elsewhere with the HF component extrapolated with the HF‐E protocol . The reference data are both USTE/AV( q , p )Z values and experimental data.…”

Section: Other Propertiesmentioning

confidence: 99%

“…All the above basis sets have in common being hierarchized, a key asset that allows us to extrapolate to the complete basis set limit (CBS) the energy (as well as any property that is relatable to the energy; the list is by no means complete, with the reader referred to recent articles from which others may be obtained through cross‐referencing) and hence estimate the basis set incompleteness error. Of course, there is a need for a reliable CBS extrapolation scheme, and here, we have chosen the one utilized in the first article of this series …”

Section: Introductionmentioning

confidence: 99%

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Optimal diffuse augmented atomic basis sets for extrapolation of the correlation energy

Varandas

Pansini

2019

Int J of Quantum Chemistry

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We seek correlation‐consistent diffuse‐augmented double‐zeta and triple‐zeta basis sets that perform optimally in extrapolating the correlation energy to the one‐electron complete basis set limit, denoted oAVXZ and oAV(X + d)Z. The novel basis sets are method‐dependent in that they are trained to perform optimally for the correlation energy at each specific level of theory. They are shown to yield accurate results in calculating both the energy and tensorial properties such as polarizabilities while not significantly altering the Hartree‐Fock energy. Quantitatively, complete basis set limit (CBS)‐/(oAVdZ,oAVtZ)‐extrapolated correlation energies typically outperform, by 3‐ to 5‐fold, the ones calculated with traditional ansatzes of similar flexibility. Attaining energies of CBS/(AVtZ,AVqZ) type or better accuracy, they frequently outperform expensive raw explicitly correlated ones. Promisingly, a limited test on CBS‐extrapolated energies based on conventional basis sets has shown that they compare well even with extrapolated explicitly correlated ones. Calculated atomization and dissociation energies, molecular geometries, ionization potentials, and electron affinities also tend to outperform the ones obtained with traditional Dunning's ansatzes from which the new basis sets have been determined. The method for basis set generation is simple, and there is no reason of principle why the approach could not be adapted for handling other bases in the literature.

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Section: Other Propertiesmentioning

confidence: 57%

Section: Other Propertiesmentioning

confidence: 99%

Section: Other Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optimal diffuse augmented atomic basis sets for extrapolation of the correlation energy

Varandas

Pansini

2019

Int J of Quantum Chemistry

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“…The C n parameter is implicitly related to the cardinality. The optimization of this parameter presents some similarity with a basis set re‐hierarchization process, which was introduced with excellent performance in the literature …”

Section: Extrapolation Formulasmentioning

confidence: 99%

Assessment of a composite method based on selected density functional theory methods and complete basis set extrapolation formulas

Chinini

Custódio

2019

Int J of Quantum Chemistry

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Extrapolation formulas based on power and exponential formulas, as well as alternatives from a Taylor series, were tested and used with density functional theory (DFT) for the calculation of enthalpies of formation. The following four functionals were analyzed: B3LYP, BMK, M06‐2X, and B2PLYP. Preliminary tests pointed to B2PLYP and B3LYP as the best and worst functionals, respectively. Taylor series expressions were as accurate as the power formulas and presented better performance than the exponential equation. The power formula (Equation (2)) and one of the simplest Taylor expressions (Equation (13)) were selected for the calculations with B3LYP and B2PLYP, with further empirical adjustments based on the higher level correction (HLC) and scaling of the experimental atomization energies used to calculate enthalpies of formation. HLC improved the B3LYP mean absolute error (MAE) from approximately 4.3 to 3.5 kcal mol−1 using both extrapolation alternatives. For B2PLY, the MAEs were improved from 2.7 to 2.6 kcal mol−1. Regarding the G3/05 test set, a significant improvement in the MAEs around 2.5 and 1.5 kcal mol−1 were achieved using B3LYP and B2PLYP, respectively. The accuracy obtained from these empirical corrections was equivalent to other composite methods. The MAEs from B3LYP and B2PLYP may be suggested as ranges for the possible accuracy to be achieved by some DFT methods. The empirical corrections suggested in this work are improvements that may be considered to provide acceptable accuracy for enthalpies of formation and possibly other properties.

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Molecules under external electric field: On the changes in the electronic structure and validity limits of the theoretical predictions

2018

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A detailed analysis of the electronic structure of the ground and first excited spin state of three diatomic molecules ( N2, BH and CO) under static applied electric field is performed at CCSD(T), DFT, MRCI and MRCI(Q) levels of theory. Our findings have revealed that by boosting the applied field one induces changes in the occupation numbers of molecular orbitals, giving rise to changes in the equilibrium geometry and in the HOMO-LUMO energy gap. Specifically, singlet to triplet spin transition can be induced by increasing the applied electric field beyond a critical value. Accordingly, affecting the accuracy of the widely used expression of energy expanded in Taylor series with respect to the applied electric field. © 2018 Wiley Periodicals, Inc.

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Application of the Unified Singlet and Triplet Electron-Pair Extrapolation Scheme with Basis Set Rehierarchization to Tensorial Properties

Cited by 15 publications

References 47 publications

Optimal diffuse augmented atomic basis sets for extrapolation of the correlation energy

Optimal diffuse augmented atomic basis sets for extrapolation of the correlation energy

Assessment of a composite method based on selected density functional theory methods and complete basis set extrapolation formulas

Molecules under external electric field: On the changes in the electronic structure and validity limits of the theoretical predictions

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