scholarly journals ExoMol line lists – XXXIX. Ro-vibrational molecular line list for CO2

2020 ◽  
Vol 496 (4) ◽  
pp. 5282-5291 ◽  
Author(s):  
S N Yurchenko ◽  
Thomas M Mellor ◽  
Richard S Freedman ◽  
J Tennyson
Keyword(s):  
Energy Surface ◽  
Transition Probabilities ◽  
Energy Operator ◽  
Nuclear Motion ◽  
Data Bases ◽  
Molecular Line ◽  
Line List ◽  
Empirical Potential ◽  
Cool Stars ◽  
Vibrational Energies

ABSTRACT A new hot line list for the main isotopologue of CO2, 12C16O2 is presented. The line list consists of almost 2.5 billion transitions between 3.5 million rotation-vibration states of CO2 in its ground electronic state, covering the wavenumber range 0–20 000 cm−1 (λ > 0.5 µm) with the upper and lower energy thresholds of 36 000 cm−1 and 16 000 cm−1, respectively. The ro-vibrational energies and wavefunctions are computed variationally using the accurate empirical potential energy surface Ames-2. The ro-vibrational transition probabilities in the form of Einstein coefficients are computed using an accurate ab initio dipole moment surface with variational program TROVE. A new implementation of TROVE which uses an exact nuclear-motion kinetic energy operator is employed. Comparisons with the existing hot line lists are presented. The line list should be useful for atmospheric retrievals of exoplanets and cool stars. The UCL-4000 line list is available from the CDS and ExoMol data bases.

scholarly journals ExoMol molecular line lists XXXVI: X 2Π – X 2Π and A 2Σ+ – X 2Π transitions of SH

2019 ◽  
Vol 490 (2) ◽  
pp. 1652-1665 ◽  
Author(s):  
Maire N Gorman ◽  
Sergei N Yurchenko ◽  
Jonathan Tennyson
Keyword(s):  
Experimental Data ◽  
Band System ◽  
Spin Orbit ◽  
Data Bases ◽  
Molecular Line ◽  
Tentative Identification ◽  
Line List ◽  
Empirical Potential ◽  
Angular Momenta ◽  
List Model

ABSTRACT The GYT line list covering rotational, rovibrational, and rovibronic transitions of the mercapto radical SH is presented. This work extends and replaces the SNaSH line list, which covers the ground (electronic) X 2Π state only. This extension is prompted by the tentative identification of the ultraviolet features of SH as being of importance in the transmission spectrum of the ultrahot Jupiter exoplanet WASP-121b. This GYT line list model is generated by fitting empirical potential energy, spin–orbit, and electronic angular momenta functions to experimentally measured wavelengths within the X 2Π and A 2Σ+ states and to the A 2Σ+–X 2Π band system using ab initio curves as a starting reference point. The fits are compatible with the quoted uncertainty of the experimental data used of ∼0.03–0.3 cm−1. The GYT line list covers wavelengths longer than 0.256 $\mu$m and includes 7686 rovibronic states and 572 145 transitions for 32SH. Line lists for the 33SH, 34SH, 36SH, and 32SD isotopologues are generated including a consideration of non-Born–Oppenheimer effects for SD. The line lists are available from the CDS (http://cdsarc.u-strasbg.fr) and ExoMol (www.exomol.com) data bases.

scholarly journals ExoMol line lists – XL. Rovibrational molecular line list for the hydronium ion (H3O+)

2020 ◽  
Vol 497 (2) ◽  
pp. 2340-2351
Author(s):  
S N Yurchenko ◽  
Jonathan Tennyson ◽  
Steve Miller ◽  
V V Melnikov ◽  
J O’Donoghue ◽  
...  
Keyword(s):  
Ab Initio ◽  
Energy Surface ◽  
Giant Planets ◽  
Vibrational States ◽  
Data Bases ◽  
Line List ◽  
Empirical Potential ◽  
Hydronium Ion ◽  
Global Fit ◽  
Transitional Probabilities

ABSTRACT A new line list for hydronium (H316O+) is computed. The line list is based on a new ab initio dipole moment surface (CCSD(T)/aug-cc-pVQZ) and a new empirical potential energy surface (PES). The empirical PES of H3O+ was obtained by refining an ab initio surface through a global fit to the experimentally determined rovibrational energies collected from the literature covering the ground, $\nu _1^{\pm }$, $\nu _2^{\pm }$, $2\nu _2^{\pm }$, $\nu _3^{\pm }$, and $\nu _4^{\pm }$ vibrational states. The line list covers the wavenumber range up to 10 000 cm−1 (wavelengths $\gt 1 \, \mu$m) and should be complete for temperatures up to T = 1500 K. This is the first comprehensive line list for H3O+ with extensive wavenumber coverage and accurate transitional probabilities. Prospects of detection of hydronium in spectra of Solar system giant planets as well as exoplanets are discussed. The eXeL line list is publicly available from the ExoMol and CDS data bases.

scholarly journals ExoMol molecular line lists – XXXV. A rotation-vibration line list for hot ammonia

2019 ◽  
Vol 490 (4) ◽  
pp. 4638-4647 ◽  
Author(s):  
Phillip A Coles ◽  
Sergei N Yurchenko ◽  
Jonathan Tennyson
Keyword(s):  
Experimental Data ◽  
Dipole Moment ◽  
High Temperature ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Data Base ◽  
Energy Surface ◽  
Molecular Line ◽  
Line List

ABSTRACT A new hot line list for 14NH3 is presented. The line list CoYuTe was constructed using an accurate, empirically refined potential energy surface and a CCSD(T)/aug-cc-pVQZ ab initio dipole moment surface of ammonia, previously reported. The line list is an improvement of the ammonia line list BYTe. The CoYuTe line list covers wavenumbers up to 20 000 cm−1, i.e. wavelengths beyond 0.5 μm for temperatures up to 1500 K. Comparisons with the high temperature experimental data from the literature show excellent agreement for wavenumbers below 6000 cm−1. The CoYuTe line list contains 16.9 billion transitions and is available from the ExoMol website (www.exomol.com) and the CDS data base.

scholarly journals ExoMol molecular line lists – XXXVII. Spectra of acetylene

2020 ◽  
Vol 493 (2) ◽  
pp. 1531-1545 ◽  
Author(s):  
Katy L Chubb ◽  
Jonathan Tennyson ◽  
Sergei N Yurchenko
Keyword(s):  
Angular Momentum ◽  
High Temperature ◽  
Electronic State ◽  
Energy Levels ◽  
Stellar Atmospheres ◽  
Ground Electronic State ◽  
Data Bases ◽  
Molecular Line ◽  
Line List ◽  
Maximum Value

ABSTRACT A new ro-vibrational line list for the ground electronic state of the main isotopologue of acetylene, 12C2H2, is computed as part of the ExoMol project. The aCeTY line list covers the transition wavenumbers up to 10 000 cm−1 (λ > 1 $\mu$m), with lower and upper energy levels up to 12 000 and 22 000 cm−1 considered, respectively. The calculations are performed up to a maximum value for the vibrational angular momentum, Kmax = Lmax  =  16, and maximum rotational angular momentum, J = 99. Higher values of J were not within the specified wavenumber window. The aCeTY line list is considered to be complete up to 2200 K, making it suitable for use in characterizing high-temperature exoplanet or cool stellar atmospheres. Einstein-A coefficients, which can directly be used to calculate intensities at a particular temperature, are computed for 4.3 billion (4 347 381 911) transitions between 5 million (5 160 803) energy levels. We make comparisons against other available data for 12C2H2, and demonstrate this to be the most complete line list available. The line list is available in electronic form from the online CDS and ExoMol data bases.

scholarly journals A semi-empirical potential energy surface and line list for H<sub>2</sub><sup>16</sup>O extending into the near-ultraviolet

2020 ◽  
Vol 20 (16) ◽  
pp. 10015-10027 ◽  
Author(s):  
Eamon K. Conway ◽  
Iouli E. Gordon ◽  
Jonathan Tennyson ◽  
Oleg L. Polyansky ◽  
Sergei N. Yurchenko ◽  
...  
Keyword(s):  
Water Molecule ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Vibrational Excitation ◽  
Special Importance ◽  
Line List ◽  
Empirical Potential ◽  
Near Ultraviolet ◽  
Semi Empirical

Abstract. Accurate reference spectroscopic information for the water molecule from the microwave to the near-ultraviolet is of paramount importance in atmospheric research. A semi-empirical potential energy surface for the ground electronic state of H216O has been created by refining almost 4000 experimentally determined energy levels. These states extend into regions with large values of rotational and vibrational excitation. For all states considered in our refinement procedure, which extend to 37 000 cm−1 and J=20 (total angular momentum), the average root-mean-square deviation is approximately 0.05 cm−1. This potential energy surface offers significant improvements when compared to recent models by accurately predicting states possessing high values of J. This feature will offer significant improvements in calculated line positions for high-temperature spectra where transitions between high J states become more prominent. Combining this potential with the latest dipole moment surface for water vapour, a line list has been calculated which extends reliably to 37 000 cm−1. Obtaining reliable results in the ultraviolet is of special importance as it is a challenging spectral region for the water molecule both experimentally and theoretically. Comparisons are made against several experimental sources of cross sections in the near-ultraviolet and discrepancies are observed. In the near-ultraviolet our calculations are in agreement with recent atmospheric retrievals and the upper limit obtained using broadband spectroscopy by Wilson et al. (2016, p. 194), but they do not support recent suggestions of very strong absorption in this region.

scholarly journals A semi-empirical potential energy surface and line list for H<sub>2</sub><sup>16</sup>O extending into the near-ultraviolet

2020 ◽  
Author(s):  
Eamon K. Conway ◽  
Iouli E. Gordon ◽  
Jonathan Tennyson ◽  
Oleg L. Polyansky ◽  
Sergei N. Yurchenko ◽  
...  
Keyword(s):  
Water Molecule ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Broad Band ◽  
Special Importance ◽  
Line List ◽  
Empirical Potential ◽  
Near Ultraviolet ◽  
Semi Empirical

Abstract. Accurate reference spectroscopic information for the water molecule from the microwave to the near-ultraviolet is of paramount importance in atmospheric research. A semi-empirical potential energy surface for the ground electronic state of H216O has been created by refining to almost 4 000 experimentally determined energy levels. These states extend into regions with large values of rotational and vibrational excitation. For all states considered in our refinement procedure, which extend to 37 000 wavenumber and J = 20, the average root mean squared deviation is approximately 0.05 wavenumber. This potential energy surface offers significant improvements when compared to recent models by accurately predicting states possessing high values of J. This feature will offer significant improvements in calculated line positions for high temperature spectra where transitions between high J states become more prominent. Combining this potential with the latest dipole moment surface for water vapor, a line list has been calculated which extends reliably to 37 000 wavenumber. Obtaining reliable results in the ultraviolet is of special importance as it is a challenging spectral region for the water molecule both experimentally and theoretically. Comparisons are made against several experimental sources of cross sections in the near-ultraviolet and discrepancies are observed. In the near-ultraviolet our calculations are in agreement with recent atmospheric retrievals and the upper limit obtained using broad band spectroscopy by Wilson et al. (J. Quant. Spectrosc. Radiat. Transf., 2016, 170, 194) but do not support recent suggestions of very strong absorption in this region.

scholarly journals Vibrational calculations in formaldehyde: the CH stretch system

2011 ◽  
Vol 9 (4) ◽  
pp. 549-556 ◽  
Author(s):  
Svetoslav Rashev ◽  
David Moule
Keyword(s):  
Large Scale ◽  
Energy Surface ◽  
Selection Procedure ◽  
Energy Operator ◽  
Basis Set ◽  
Kinetic Energy Operator ◽  
Vibrational Levels ◽  
Lanczos Iteration ◽  
Vibrational Energies ◽  
Vibrational Kinetic

AbstractAn alternative procedure for the calculation of highly excited vibrational levels in S0 formaldehyde was developed to apply to larger molecules. It is based on a new set of symmetrized vibrational valence coordinates. The fully symmetrized vibrational kinetic energy operator is derived in these coordinates using the Handy expression [Molec. Phys. 61, 207 (1987)]. The potential energy surface is expressed as a fully symmetrized quartic expansion in the coordinates. We have performed ab initio electronic computations using GAMESS to obtain all force constants of the S0 formaldehyde quartic force field. Our large scale vibrational calculations are based on a fully symmetrized vibrational basis set, in product form. The vibrational levels are calculated one by one using an artificial intelligence search/selection procedure and subsequent Lanczos iteration, providing access to extremely high vibrational energies. In this work special attention has been given to the CH stretch system by calculating the energies up to the fifth CH stretch overtone at ∼16000 cm−1, but the method has also been tested on two highly excited combination levels including other lower frequency modes.

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