The Sc2 dimer revisited

Καλέμος, Απόστολος; Kaplan, I. G.; Mavridis, Aristides

doi:10.1063/1.3290951

Cited by 30 publications

(45 citation statements)

References 48 publications

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“…This results in physically acceptable global PECs for all 30 molecular states correlating to the lowest dissociation limit. Predicted spectroscopic parameters are in reasonable agreement with earlier MRCI calculations [22].…”

Section: G Term Corresponding To An [Ar]4ssupporting

confidence: 79%

“…The short range of the potential is characterized by spectroscopic constants, of which the equilibrium distance, R e , well depth, D e , and harmonic frequency, ω e , are listed in Table V. For comparison, this table also includes the results of Kalemos et al [22] at the MRCI/cc-pVQZ level of theory. Experimental data are not yet available for the studied states.…”

Section: Analytical Representationmentioning

confidence: 99%

“…Since the ground state is a quintet spin state, it is not coupled to the states studied in this work by the nonrelativistic electronic interaction. To our knowledge, the only study of the electronic states that correlate to the lowest dissociation channel are the multireference configuration interaction (MRCI) calculations by Kalemos et al [22]. This method is not size-consistent, which leads to inaccuracy in the long-range regime.…”

Section: G Term Corresponding To An [Ar]4smentioning

confidence: 99%

“…The large spatial extent of the filled 4s subshell prevents covalent bonding. The bonding is therefore expected to be predominantly due to the dispersion interaction, making an accurate description of electronic correlation effects essential [22]. Moreover, the submergedshell structure is thought to suppress the interaction anisotropy, leading to energetically closely spaced adiabatic states.…”

Section: G Term Corresponding To An [Ar]4smentioning

confidence: 99%

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Cold magnetically trapped2Dgscandium atoms. I. Interaction potential

2014

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We present a first principles description of the interaction of two ground-state scandium atoms. Scandium has a 2 D g ground state. Thirty molecular states correlate to the lowest dissociation limit of the dimer. In the short range, potential energy curves are calculated using second-order n-electron valence state perturbation theory. The first-order long-range interaction is calculated at the complete active space self-consistent field level. We determine the second-order long-range dispersion interaction from atomic dynamic polarizabilities at imaginary frequencies. These polarizabilities are calculated using time-dependent density functional theory. We merge the short-range approach with the long-range model to obtain a physical description of the 30 potential energy curves correlating to the 2 D g + 2 D g limit. Diabatic potentials are presented that can be used in quantum scattering calculations, in order to study Zeeman relaxation of ultracold scandium atoms.

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Section: G Term Corresponding To An [Ar]4ssupporting

confidence: 79%

Section: Analytical Representationmentioning

confidence: 99%

Section: G Term Corresponding To An [Ar]4smentioning

confidence: 99%

Section: G Term Corresponding To An [Ar]4smentioning

confidence: 99%

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Cold magnetically trapped2Dgscandium atoms. I. Interaction potential

2014

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“…A change of the shift parameter in the intruder state removal techniques can lead to a change of the order of states, as was demonstrated in [58] just for Sc 2 . Thus, the conclusion of Matxain et al [43] had to be verified in more precise calculations, which has been done in publications [44,45].…”

Section: Account Of Published Studiesmentioning

confidence: 98%

Multi-reference Ab initio calculations of 3d transition-metal dimers: Sc2

Kaplan

Miranda

2014

Russ. J. Phys. Chem.

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The problem of calculation of the electronic structure of transition metal clusters (even dimers) still presents a challenge for computational chemistry. The reason is that the expansion of the ground state wave function on electronic configurations does not contain a principal configuration and a large number of reference configurations must be treated equally. Thus, the multi reference (MR) approaches are, in general, mandatory. A short description of the MRCI methods is presented. The calculation of Sc 2 at the MRCISD(+Q)/cc pV5Z level, showed that the its ground state corresponds to a quintet, , in agreement with experiment and previous precise calculations. The triplet state is located about 1.1 kcal/mol above.We calculated the ground state, X , of the Sc 2 dimer by the MRCISD(+Q) method at the complete basis set (CBS) limit. This is the first MRCISD(+Q) calculation of 3d transition metal clusters at the CBS limit. From the Mulliken population analysis and comparison with atomic energies follows that in the ground state Sc 2 dissociates on one Sc in the ground state and the other in the second excited quartet state, 4 F u . The spec troscopic parameters of the ground potential curve, obtained by the Dunham analysis at the valence MRCISD(+Q)/CBS level, are: R e = 5.20 bohr, D e = 50.37 kcal/mol, and e = 234.5 cm -1 . The obtained value for the harmonic frequency agrees very well with the experimental one, e = 239.9 cm -1 . From the indistin guishability of identical atoms in quantum mechanics follows that in spite of an asymmetric dissociation limit for Sc 2 , both Sc atoms have the same electron population and it is incorrect to consider them as different. Therefore, the accepted classification of the dimer states should be revised, since some of them are forbidden by the Pauli Exclusion Principle.Keywords: 3d transition metal dimers, Sc 2 , multi reference configuration interaction (MRCI), complete basis set limit.

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Eliminating symmetry problems in electronegativity equalization and correcting self‐interaction errors in conceptual DFT

Szentpály

2018

J Comput Chem

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The chemical potential is by definition constant in molecules, and electronic charge is in principle equilibrated by bonding. Does electronegativity offer the best scale to unify these principles? According to conceptual density functional theory (c-DFT), the electronegativity equalization (ENE) and chemical potential equalization (CPE) principles seem rigorous and identical. However, the operational formulations of CPE and ENE fail to validate this claim, and frequently dramatic deviations from equalization are reported. We here eliminate the deviations to a very large extent. The problems originate from (i) c-DFT's exclusive reference to ground states and violations of the Wigner-Witmer symmetry constraints for bonding, (ii) electron self-interaction and delocalization errors. The problems are solved, and much more accurate ENE and bond polarities are obtained by replacing the ground-state electronegativity (χ ) by the valence-state electronegativity (χ ) and its generalization, the valence-pair-affinity (VPA, α ). The VPA is a charge dependent pair-sharing potential connected to Ruedenberg's bond theory that emphasizes the role of electron pair-density. The performances of the valence-pair equilibration (VPEq) and c-DFT's operational CPE are compared for 89 molecules with very diverse bond characters, including the "exotic" dimers Be , Mg , B , C , and Mn . The accuracy of VPEq is about 9 times better than that of operational CPE. Without requiring ad hoc calibrations, the VPEq bond polarities agree very well with results of state-of-the-art population analyses, and charges derived from vibrational spectra. A paradigm shift emphasizing valence states seems in order for c-DFT. Electronegativity and the chemical potential should be regarded as separate properties. Copyright © 2018 Wiley Periodicals, Inc.

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The Sc2 dimer revisited

Cited by 30 publications

References 48 publications

Cold magnetically trapped2Dgscandium atoms. I. Interaction potential

Cold magnetically trapped2Dgscandium atoms. I. Interaction potential

Multi-reference Ab initio calculations of 3d transition-metal dimers: Sc2

Eliminating symmetry problems in electronegativity equalization and correcting self‐interaction errors in conceptual DFT

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