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

Amaral, Paulo H. R.; Mohallem, José R.

doi:10.1063/1.4983394

Cited by 3 publications

(13 citation statements)

References 37 publications

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“…These effective masses are to be used in the rovibrational nuclear equation to account for the non-adiabatic effects in the calculations of the rovibrational energy levels. As shown in Amaral & Mohallem (2017), this accounting for the nonadiabatic effects is so far the most accurate for the systems studied in that work. In the procedure there is no need to use any empirical scaling of the correction curves, such as, for example, the scaling used in Diniz et al (2012).…”

Section: Non-adiabatic Effects On the Energy Levelsmentioning

confidence: 85%

“…The iterative procedure called ISA (iterated stockholder atoms, Lillestonen & Wheatley 2008), which is explained in Amaral & Mohallem (2017), allows determination of the SAIM densities of atoms A and B, ρ A and ρ B . The sum of these densities is the molecular density…”

Section: Non-adiabatic Effects On the Energy Levelsmentioning

confidence: 99%

“…r , is chosen as the part of the whole SAIM density preponderantly subject to the potential V A , that is, corresponding to the region where V A is more attractive than V B (Figure 4 of Amaral & Mohallem (2017) illustrates this feature). The same procedure is followed to obtain the core fraction of the CVSAIM density of atom B, c B, r .…”

Section: Non-adiabatic Effects On the Energy Levelsmentioning

confidence: 99%

“…It should be noted that for homonuclear molecules the cores are easily identified as the non-superposed parts of the CVSAIM densities. Then, the superposing part of the densities correspond to the stationary density of the valence electrons (see Figure 1 in Amaral & Mohallem 2017).…”

Section: Non-adiabatic Effects On the Energy Levelsmentioning

confidence: 99%

“…The progress in the PEC calculations includes implementation of improved procedures for calculating the leading relativistic corrections. The progress in calculating the nonadiabatic effects includes implementation of a procedure based the atoms-in-molecules (AIM) core-valence partition of the electronic density (Amaral & Mohallem 2017). The partition allows for the determination of the fractions of the electron density that needs to be added to the nuclear masses to produce the effective vibrational reduced masses.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

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: Non-adiabatic Effects On the Energy Levelsmentioning

confidence: 85%

Section: Non-adiabatic Effects On the Energy Levelsmentioning

confidence: 99%

Section: Non-adiabatic Effects On the Energy Levelsmentioning

confidence: 99%

Section: Non-adiabatic Effects On the Energy Levelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Amaral

Diniz

Jones

et al. 2019

ApJ

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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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Non-adiabatic effects in the H ₃ ⁺ spectrum

Amaral

Stanke

Adamowicz

et al. 2019

Phil. Trans. R. Soc. A.

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The effect of non-adiabatic coupling on the computed rovibrational energy levels amounts to about 2 cm −1 for H 3 + and must be included in high-accuracy calculations. Different strategies to obtain the corresponding energy shifts are reviewed in the article. A promising way is to introduce effective vibrational reduced masses that depend on the nuclear configuration. A new empirical method that uses the stockholder atoms-in-molecules approach to this effect is presented and applied to H 3 + . Furthermore, a highly accurate potential energy surface for the D 3 + isotopologue, which includes relativistic and leading quantum electrodynamic terms, is constructed and used to analyse the observed rovibrational frequencies for this molecule. Accurate band origins are obtained that improve existing data. This article is part of a discussion meeting issue ‘Advances in hydrogen molecular ions: H 3 + , H 5 + and beyond’.

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

Cited by 3 publications

References 37 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

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

Non-adiabatic effects in the H ₃ ⁺ spectrum

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

Cited by 3 publications

References 37 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

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

Non-adiabatic effects in the H 3 + spectrum

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Product

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Non-adiabatic effects in the H ₃ ⁺ spectrum