A global, high accuracy <i>ab initio</i> dipole moment surface for the electronic ground state of the water molecule

Lodi, Lorenzo; Tennyson, Jonathan; Polyansky, Oleg L.

doi:10.1063/1.3604934

Cited by 165 publications

(148 citation statements)

References 36 publications

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“…Ab initio studies of small polyatomic molecules emerged in the past decades with drastically improved computational methods and hardware resources. A breakthrough in predicting rotationally resolved spectra of small molecules was made possible by accurate electronic structure calculations of the molecular PESs and DMSs (see, e.g., Partridge & Schwenke 1997;Cours et al 2002;Yurchenko et al 2009;Nikitin et al 2009;Lodi et al 2011;Császár et al 2010;Szalay et al 2011;Huang et al 2011aHuang et al , 2012Sousa-Silva et al 2014;Nikitin et al 2014;Li et al 2014;Delahaye et al 2015) and by developing efficient methods for quantum nuclear motion calculations (see Schwenke & Partridge 2001;Schwenke 2002;Cassam-Chenaï et al 2012;Yurchenko et al 2007;Wang & Carrington Jr. 2013a,b;Carter et al 2009;Rey et al 2012;Bowman et al 2005). In case of triatomics, such as water isotopic species (Yurchenko et al 2009;Barber et al 2011), carbon dioxide (Huang et al 2013(Huang et al , 2014, and ozone accurate theoretical predictions led to significant extensions of spectral analyses toward higher energy ranges.…”

Section: Theory and Computational Methodsmentioning

confidence: 99%

First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

Rey

Delahaye

Nikitin

et al. 2016

A&A

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We present the construction of complete and comprehensive ethylene line lists for the temperatures 50−700 K based on accurate ab initio potential and dipole moment surfaces and extensive first-principle calculations. Three lists spanning the [0−6400] cm −1 infrared region were built at T = 80, 160, and 296 K, and two lists in the range [0−5200] cm −1 were built at 500 and 700 K. For each of these five temperatures, we considered possible convergence problems to ensure reliable opacity calculations. Our final list at 700 K was computed up to J = 71 and contains almost 60 million lines for intensities I > 5 × 10 −27 cm/molecule. Comparisons with experimental spectra carried out in this study showed that for the most active infrared bands, the accuracy of band centers in our theoretical lists is better on average than 0.3 cm −1 , and the integrated absorbance errors in the intervals relevant for spectral analyses are about 1−3%. These lists can be applied to simulations of absorption and emission spectra, radiative and non-LTE processes, and opacity calculations for planetary and astrophysical applications.

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Section: Theory and Computational Methodsmentioning

confidence: 99%

First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

Rey

Delahaye

Nikitin

et al. 2016

A&A

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“…In particular, the fitting procedure developed allowed us to fit the band origins of the water monomer up to 40 000 cm −1 to an accuracy of 0.086 cm −1 , close to the experimental one, as a first stage of the fitting of the global water PES with excited rotational energy levels J up to 2. The global LTP2011 DMS calculated by Lodi et al [76] allows both extremely accurate calculations of intensities of conventional spectral lines up to 26 000 cm −1 and calculations of Stark coefficients of the levels up to dissociation. The preliminary results of such calculations show excellent agreement with experiment.…”

Section: Discussionmentioning

confidence: 99%

“…The wave functions of these levels were calculated using the DVR3D nuclear motion code with the fitted PES12 PES [37]. These wave functions were used as input data for a program computing line strengths using both the published CVR DMS [69] and our new DMS given by Lodi et al [76]. The line strengths, together with line positions, are used to obtain the calculated values of the Stark coefficients.…”

Section: Accurate Global Dipole Moment Surface and Stark Coefficient mentioning

confidence: 99%

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Global spectroscopy of the water monomer

Polyansky

Zobov

Mizus

et al. 2012

Phil. Trans. R. Soc. A.

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Given the large energy required for its electronic excitation, the most important properties of the water molecule are governed by its ground potential energy surface (PES). Novel experiments are now able to probe this surface over a very extended energy range, requiring new theoretical procedures for their interpretation. As part of this study, a new, accurate, global spectroscopic-quality PES and a new, accurate, global dipole moment surface are developed. They are used for the computation of the high-resolution spectrum of water up to the first dissociation limit and beyond as well as for the determination of Stark coefficients for high-lying states. The water PES has been determined by combined ab initio and semi-empirical studies. As a first step, a very accurate, global, ab initio PES was determined using the all-electron, internally contracted multi-reference configuration interaction technique together with a large Gaussian basis set. Scalar relativistic energy corrections are also determined in order to move the energy determinations close to the relativistic complete basis set full configuration interaction limit. The electronic energies were computed for a set of about 2500 geometries, covering carefully selected configurations from equilibrium up to dissociation. Nuclear motion computations using this PES reproduce the observed energy levels up to 39 000 cm −1 with an accuracy of better than 10 cm −1 . Line positions and widths of resonant states above dissociation show an agreement with experiment of about 50 cm −1 . An improved semi-empirical PES is produced by fitting the ab initio PES to accurate experimental data, resulting in greatly improved accuracy, with a maximum deviation of about 1 cm −1 for all vibrational band origins. Theoretical results based on this semi-empirical surface are compared with experimental data for energies starting at 27 000 cm −1 , going all the way up to dissociation at about 41 000 cm −1 and a few hundred wavenumbers beyond it.

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“…The Hellmann-Feynman theorem shows that these two methods are equivalent for exact wavefunctions. High accuracy tends to favor the use of finite differences despite the extra computational cost: the finite difference method is more accurate but, perhaps more importantly, as an energy-based method it allows small corrections to the DMS to be introduced along the lines of the FPA procedure used for PES 123,124 even for corrections which use first-order perturbation theory.…”

Section: Heavier Systemsmentioning

confidence: 99%

Perspective: Accurate ro-vibrational calculations on small molecules

Tennyson

2016

The Journal of Chemical Physics

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In what has been described as the fourth age of quantum chemistry, variational nuclear motion programs are now routinely being used to obtain the vibration-rotation levels and corresponding wavefunctions of small molecules to the sort of high accuracy demanded by comparison with spectroscopy. In this perspective, I will discuss the current state-of-the-art which, for example, shows that these calculations are increasingly competitive with measurements or, indeed, replacing them and thus becoming the primary source of data on key processes. To achieve this accuracy ab initio requires consideration of small effects, routinely ignored in standard calculations, such as those due to quantum electrodynamics. Variational calculations are being used to generate huge lists of transitions which provide the input for models of radiative transport through hot atmospheres and to fill in or even replace measured transition intensities. Future prospects such as the study of molecular states near dissociation, which can provide a link with low-energy chemical reactions, are discussed. Published by AIP Publishing. [http://dx

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A global, high accuracy ab initio dipole moment surface for the electronic ground state of the water molecule

Cited by 165 publications

References 36 publications

First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

Global spectroscopy of the water monomer

Perspective: Accurate ro-vibrational calculations on small molecules

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A global, high accuracy ab initio dipole moment surface for the electronic ground state of the water molecule

Cited by 165 publications

References 36 publications

First theoretical global line lists of ethylene (12C2H4) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

First theoretical global line lists of ethylene (12C2H4) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

Global spectroscopy of the water monomer

Perspective: Accurate ro-vibrational calculations on small molecules

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Product

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First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres