Connecting a new non-adiabatic vibrational mass to the bonding mechanism of LiH: A quantum superposition of ionic and covalent states

Diniz, Leonardo G.; Alijah, Alexander; Adamowicz, Ludwik; Mohallem, José R.

doi:10.1016/j.cplett.2015.04.062

Cited by 6 publications

(17 citation statements)

References 27 publications

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“…In the calculations very accurate PEC and dipole moment curves (DMC) reported before (Diniz et al 2016) were employed. The non-adiabatic corrections were obtained with the use of a constant reduced nuclear mass for rotations and a R-dependent mass taken from Diniz et al (2015; obtained in valence-bond calculations) for vibrations.…”

Section: Introductionmentioning

confidence: 99%

Benchmark Rovibrational Linelists and Einstein A-coefficients for the Primordial Molecules and Isotopologues

Amaral

Diniz

Jones

et al. 2019

ApJ

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Complete benchmark rovibrational energy linelists calculated for the primordial polar molecules of the universe, namely HD + , HD, and the HeH + isotopologues, with accuracy up to 10 −2 cm −1 for low-lying states, are presented. To allow for these calculations to be performed, new high-accuracy potential energy curves, which include the diagonal Born-Oppenheimer adiabatic corrections and the leading relativistic corrections, are determined. Also, a new approach for calculating non-adiabatic corrections involving an effective vibrational nuclear mass obtained based on the atoms-in-molecules theory is employed. The vibrational and rotational masses are taken as being different and dependent on the nuclear distance. Accurate dipole moment curves are calculated and used to generate lists of Einstein A-coefficients. The energy linelists and the sets of Einstein A-coefficients for HD are upgrades of previous calculations including quasibound states, while for HD + and HeH + and its isotopologues the present results represent significant improvement over the previous calculations. The results obtained here suggest that, with the inclusion of the non-adiabatic corrections, the accuracy limit at least for low-lying states might have been reached. Thus, further progress should involve accounting for even smaller effects such as the quantumelectrodynamics corrections. The present results represent the state-of-the-art of theoretical spectroscopy of the primordial polar molecules.

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Section: Introductionmentioning

confidence: 99%

Benchmark Rovibrational Linelists and Einstein A-coefficients for the Primordial Molecules and Isotopologues

Amaral

Diniz

Jones

et al. 2019

ApJ

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“…This feature led us previously to conclude for the lack of a valence (in the classical sense) electron fraction and that the cores would exchange electron fractions directly between themselves. 20 On the other hand, we see now that the Li core is really the full Li SAIM, having the recognized charge of +0.90 a.u. at R eq = 3.0 a.u., but there is also a valence part (in the present quantitative sense) belonging exclusively to the H SAIM.…”

Section: Lihmentioning

confidence: 82%

“…The advantage of the present approach over the older one 20 is the general and well-founded obtaining of core masses from SAIM. In consequence, no guessing for µ(R) or scaling of the corrections, as in Ref.…”

Section: Lihmentioning

confidence: 98%

“…Application to LiH as well as improvement of the results for H 2 was possible by extracting the core masses from the coefficients of suitably chosen valence-bond structures. 20 However, these wavefunction-dependent applications suffer from the lack of a common approach. For example, the recipes for core masses from VB Ansätze that worked for LiH and H 2 are not consistent between themselves, meaning that the basis for these successful applications is not yet fully understood.…”

Section: Effective Potentials For Saim and Core Massesmentioning

confidence: 99%

“…The PEC is the same as that used in Ref. 20, including not only DBOCs but also relativistic corrections. The nonadiabatic corrections are obtained in the same way as for HeH + and are then added to the vibrational levels, leading to stringent agreement with experimental results, as shown in Figure 7.…”

Section: Lihmentioning

confidence: 99%

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Core-valence stockholder AIM analysis and its connection to nonadiabatic effects in small molecules

Amaral

Mohallem

2017

The Journal of Chemical Physics

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A previous theory of separation of motions of core and valence fractions of electrons in a molecule [J. R. Mohallem et al., Chem. Phys. Lett. 501, 575 (2011)] is invoked as basis for the useful concept of Atoms-in-Molecules (AIM) in the stockholder scheme. The output is a new tool for the analysis of the chemical bond that identifies core and valence electron density fractions (core-valence stockholder AIM (CVSAIM)). One-electron effective potentials for each atom are developed, which allow the identification of the parts of the AIM which move along with the nuclei (cores). This procedure results in a general method for obtaining effective masses that yields accurate non-adiabatic corrections to vibrational energies, necessary to attain cm accuracy in molecular spectroscopy. The clear-cut determination of the core masses is exemplified for either homonuclear (H, H) or heteronuclear (HeH, LiH) molecules. The connection of CVSAIM with independent physically meaningful quantities can resume the question of whether they are observable or not.

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Physical versus non‐physical effective nuclear masses for non‐adiabatic corrections to molecular spectra

Pinto,

Amaral,

Diniz

et al. 2023

Int J of Quantum Chemistry

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Two types of developments for very accurate non‐adiabatic corrections to rovibrational molecular energy levels, one of a formal nature and the other of a heuristic nature, lead to fundamentally different approaches for effective nuclear masses. The former yields effective masses that have non‐physical interpretation at some ranges of nuclear distances. The later uses physical masses obtained from electronic structure calculations. This paper contains a brief review of the subject and proposes procedures to improve and generalize the heuristic approach. Comparisons are made of the results obtained by the two approaches for the H molecule, since no further calculations were found with the proper accuracy, but some issues involving the HeH ion and the water molecule are discussed. The conclusion is that the heuristic approach has many advantages over the formal one, namely, equivalent accuracy and physically grounded qualitative interpretation. But, moreover, it seems to be presently the only method that allows non‐adiabatic calculations for well isolated states of larger molecules.

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Connecting a new non-adiabatic vibrational mass to the bonding mechanism of LiH: A quantum superposition of ionic and covalent states

Cited by 6 publications

References 27 publications

Benchmark Rovibrational Linelists and Einstein A-coefficients for the Primordial Molecules and Isotopologues

Benchmark Rovibrational Linelists and Einstein A-coefficients for the Primordial Molecules and Isotopologues

Core-valence stockholder AIM analysis and its connection to nonadiabatic effects in small molecules

Physical versus non‐physical effective nuclear masses for non‐adiabatic corrections to molecular spectra

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