High-Accuracy ab Initio Rotation-Vibration Transitions for Water

Polyansky, Oleg L.; Császár, Attila G.; Shirin, Sergei V.; Zobov, Nikolai F.; Barletta, Paolo; Tennyson, Jonathan; Schwenke, David W.; Knowles, Peter J.

doi:10.1126/science.1079558

Cited by 292 publications

(203 citation statements)

References 26 publications

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“…This makes it necessary to include these corrections in calculations if high accuracy is to be achieved. Building a high-accuracy composite PES meant that about 20 000 experimentally known levels belonging to five water isotopologues could be matched via a first-principles approach with a standard deviation of 1 cm −1 [6,60]. Again, this work was limited to levels below 26 000 cm −1 , as this limit was determined by the highest energy levels known experimentally at the time.…”

Section: Conventional Spectra Of the Water Monomermentioning

confidence: 99%

“…We used the composite, adiabatic CVRQD ab initio PES [6,60] as a starting point during several attempts to improve the accuracy of spectroscopically determined PESs [16,37,39]. The first attempt by Shirin et al [16] gave a standard deviation of 0.08 cm −1 between computed and measured rovibrational energies.…”

Section: Conventional Spectra Of the Water Monomermentioning

confidence: 99%

“…For relatively highly excited vibrations, the errors were of the order of 20 cm −1 , and it became clear that fitting required a significantly better ab initio starting point. Before our recent determination of the global ab initio surface, the most accurate ab initio PES of the water monomer was obtained by Polyansky et al [6]. At that time, we used the electronic structure package MOLPRO [55] with the internally contracted multi-reference configuration interaction (IC-MRCI) method and an aug-cc-pV6Z Gaussian basis set with complete basis set extrapolation for determining a pure Born-Oppenheimer (BO) PES.…”

Section: Conventional Spectra Of the Water Monomermentioning

confidence: 99%

“…The grid points used to construct the CVRQD ab initio PES [6,60] were not designed for calculations of spectra up to dissociation. Execution of a new set of ab initio electronic structure computations was therefore deemed necessary.…”

Section: Water Spectrum Up To Dissociationmentioning

confidence: 99%

“…It was one of the first polyatomic molecules for which variational calculations were performed by Whitehead & Handy [5]. It was also the first polyatomic and polyelectronic system to be treated with close to spectroscopic accuracy [6]; for which relativistic and quantum electrodynamic (QED) effects were computed [7][8][9][10]; and for which very accurate ab initio and semi-empirical potential energy surfaces (PESs) were developed. At present, it is one of the few chemically bound polyatomic molecules for which the spectra up to dissociation and above have been observed.…”

Section: Introductionmentioning

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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Section: Conventional Spectra Of the Water Monomermentioning

confidence: 99%

Section: Conventional Spectra Of the Water Monomermentioning

confidence: 99%

Section: Conventional Spectra Of the Water Monomermentioning

confidence: 99%

Section: Water Spectrum Up To Dissociationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Global spectroscopy of the water monomer

Polyansky

Zobov

Mizus

et al. 2012

Phil. Trans. R. Soc. A.

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AbInitio Theory for Accurate Spectroscopic Constants and Molecular Properties

Tew

Klopper

Bachorz

et al. 2011

Handbook of High‐resolution Spectroscopy

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Having access to highly accurate potential energy surfaces (PESs) is a prerequisite for the ab initio calculation of accurate spectroscopic constants and molecular properties. The construction of such surfaces, however, is a formidable task. It not only requires solving of the time‐independent, nonrelativistic, clamped‐nuclei, electronic Schrödinger equation of the molecular n ‐electron system at the highest possible level of approximation, but it also requires inclusion of small energy terms that are often neglected at other occasions. Such terms are, for example, due to nonadiabatic and relativistic effects (scalar and nonscalar). Nevertheless, the largest sources of error in calculating PESs are most often due to the inadequate description of the nonrelativistic electronic wave function of the molecular n ‐electron system in the Born–Oppenheimer approximation. This article is concerned with these sources of error, which are related to the truncation of the one‐electron basis set of atomic functions and to the incomplete expansion of the wave function in a basis of n ‐electron functions. In particular, these errors diminish only extremely slowly with the extension of the one‐electron basis set when the wave function is expanded in terms of n ‐electron functions that are (antisymmetrized) products of one‐electron functions (orbitals). Coupled‐cluster theory in conjunction with explicitly correlated two‐electron geminals (instead of the more commonly used products of two orbitals) appears to be a promising approach toward obtaining an adequate description of the clamped‐nuclei, nonrelativistic electronic wave function and, thus, for the calculation of highly accurate PESs, from which accurate spectroscopic constants and molecular properties may be obtained.

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Prediction of Vibrational Spectra fromAbInitio Theory

Breidung

Thiel

2011

Handbook of High‐resolution Spectroscopy

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Ab initio electronic structure theory provides potential energy and dipole moment surfaces that can be used to compute rovibrational term values and transition moments, either by normal mode analysis followed by rovibrational perturbation theory or through variational calculations. The accuracy of the theoretical spectra thus generated depends on the level of electronic structure theory and the nuclear motion treatment applied. This review surveys the currently available theoretical methods and their accuracy. Case studies are discussed to illustrate the present state of the art.

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High-Accuracy ab Initio Rotation-Vibration Transitions for Water

Cited by 292 publications

References 26 publications

Global spectroscopy of the water monomer

Global spectroscopy of the water monomer

AbInitio Theory for Accurate Spectroscopic Constants and Molecular Properties

Prediction of Vibrational Spectra fromAbInitio Theory

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