The electronic ground states of alkali monoxides

So, Suk Ping; Richards, W. Graham

doi:10.1016/0009-2614(75)85109-8

Cited by 57 publications

(16 citation statements)

References 16 publications

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“…Ab initio conÐguration interaction (CI) calculations by Allison et al11,12 deduced that the 2&`state was lower than the 2% state by 114 cm~1, while Langho † et al 18 obtained 650 cm~1 using a larger CI ; lowerlevel HartreeÈFock (HF) values of 606 cm~1 (ref. 19) and 515 cm~1 (ref. 18) have also been reported.…”

Section: Introduction (A) Backgroundmentioning

confidence: 99%

An ab initio study of RbO, CsO and FrO (X2Î£+; A2Î ) and their cations (X3Î£â€“; A3Î )

Lee

Lozeille

Soldán

et al. 2001

Phys. Chem. Chem. Phys.

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Section: Introduction (A) Backgroundmentioning

confidence: 99%

An ab initio study of RbO, CsO and FrO (X2Î£+; A2Î ) and their cations (X3Î£â€“; A3Î )

Lee

Lozeille

Soldán

et al. 2001

Phys. Chem. Chem. Phys.

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“…This is of particular interest for the alkali oxides, where there is a. change in ground-state symmetry from LiO( 2 Il) to CsO( 2 E + ). For the KO molecule there is both conflicting experimental [12][13] and theoretical [14][15] ""Hi! 1 ?…”

mentioning

confidence: 99%

Theoretical Dissociation Energies for Ionic Molecules

Langhoff

Bauschlicher

Partridge

1985

Comparison of Ab Initio Quantum Chemistry With Experiment for Small Molecules

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Ab initio calculations at the self-consistent-field and singles plus doubles configuration-interaction level are used to determine accurate spectroscopic parameters (D e , r e , u e ) for most of the alkali and alkaline-earth fluorides, chlorides, oxides, sulfides, hydroxides and isocyanides. Numerical Hartree-Fock (NHF) calculations are performed on selected systems to ensure that the extended Slater basis sets employed for the diatomic systems are near the Hartree-Fock limit. Extended gaussian basis sets of at least triple-zeta plus double polarization quality are employed for the triatomic systems. By dissociating to the ionic limits, most of the differential correlation effects can be embedded in the accurate experimental electron affinities and ionization potentials. With this model, correlation effects are relatively small (0.0-0.3 eV), but invariably increase D 0 . The importance of correlating the electrons on both the anion and the metal is discussed.The theoretical dissociation energies (D 0 ) are critically compared with the literature to rule out disparate experimental values. The theoretical studies combined with the experimental literature allow us to recommend D 0 values that are accurate to 0.1 eV for all systems considered. The systematic treatment of many different systems reveal many trends. For example, the dissociation energies of the alkali and alkaline-earth hydroxides are observed to be less than the corresponding fluorides by just slightly less than the difference in electron affinities of F and OH. In general, there is a strong correlation between the dissociation energy (to ions) and r e , because the bonding is predominantly electrostatic in origin.

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“…The agreement of all methods suggests that potentially inaccurate or imprecise experimental reference values should be revisited. For NaO 86,87 and F -2 , 85 the reference data given by Huber and Herzberg 69 are sourced from calculations performed at the HF level of theory; any of the CCSD(T) methods surveyed should be seen as a more accurate result for these systems. For another subset of these systems the error bars on the experimental values contain the frequencies calculated from this work (PH -: 2230 ± 100 cm −1 , 91 PO -: 1000 ± 70 cm −1 , 91 LiCl -: 480 ± 80 cm −1 93 ).…”

Section: Potential Issues With Experimental Datamentioning

confidence: 99%

Polishing the Gold Standard: The Role of Orbital Choice in CCSD(T) Vibrational Frequency Prediction

Bertels,

Lee,

Head-Gordon

2020

Preprint

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While CCSD(T) with spin-restricted Hartree-Fock (RHF) orbitals has long been lauded for its ability to accurately describe closed-shell interactions, the performance of CCSD(T) on open-shell species is much more erratic, especially when using a spinunrestricted HF (UHF) reference. Previous studies have shown improved treatment of open-shell systems when a non-HF set of molecular orbitals, like Brueckner or Kohn-Sham density functional theory (DFT) orbitals, is used as a reference. Inspired by the success of regularized orbital-optimized second-order Møller-Plesset perturbation theory (κ-OOMP2) orbitals as reference orbitals for MP3, we investigate the use of κ-OOMP2 orbitals and various DFT orbitals as reference orbitals for CCSD(T) calculations of the corrected ground-state harmonic vibrational frequencies of a set of 36 closed-shell (29 neutrals, 6 cations, 1 anion) and 59 open-shell diatomic species (38 1 neutrals, 15 cations, 6 anions). The aug-cc-pwCVTZ basis set is used for all calculations. The use of κ-OOMP2 orbitals in this context alleviates difficult cases observed for both UHF orbitals and OOMP2 orbitals. Removing 2 multireference systems and 12 systems with ambiguous experimental data leaves a pruned data set. Overall performance on the pruned data set highlights CCSD(T) with a B97 orbital reference (CCSD(T):B97), CCSD(T) with a κ-OOMP2 orbital reference (CCSD(T):κ-OOMP2), and CCSD(T) with a B97M-rV orbital reference (CCSD(T):B97M-rV) with RMSDs of 8.48 cm −1 and 8.50 cm −1 , and 8.75 cm −1 respectively, outperforming CCSD(T):UHF by nearly a factor of 5. Moreover, the performance on the closed-and open-shell subsets show these methods are able to treat open-shell and closed-shell systems with comparable accuracy and robustness. The use of κ-OOMP2 orbitals has also proven useful in diagnosing multireference character that can hinder the reliability of CCSD(T).

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The electronic ground states of alkali monoxides

Cited by 57 publications

References 16 publications

An ab initio study of RbO, CsO and FrO (X2Î£+; A2Î ) and their cations (X3Î£â€“; A3Î )

An ab initio study of RbO, CsO and FrO (X2Î£+; A2Î ) and their cations (X3Î£â€“; A3Î )

Theoretical Dissociation Energies for Ionic Molecules

Polishing the Gold Standard: The Role of Orbital Choice in CCSD(T) Vibrational Frequency Prediction

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