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 ExoMol line lists – XLI. High-temperature molecular line lists for the alkali metal hydroxides KOH and NaOH

2021 ◽  
Author(s):  
A Owens ◽  
J Tennyson ◽  
S N Yurchenko
Keyword(s):  
High Temperature ◽  
Alkali Metal ◽  
First Principles ◽  
Spectroscopic Data ◽  
Potassium Hydroxide ◽  
Energy Levels ◽  
Rotational Excitation ◽  
Molecular Line ◽  
Metal Hydroxides ◽  
Line List

Abstract Potassium hydroxide (KOH) and sodium hydroxide (NaOH) are expected to occur in the atmospheres of hot rocky super-Earth exoplanets but a lack of spectroscopic data is hampering their potential detection. Using robust first-principles methodologies, comprehensive molecular line lists for KOH and NaOH that are applicable for temperatures up to T = 3500 K are presented. The KOH OYT4 line list covers the 0 – 6000 cm−1 (wavelengths λ > 1.67 μm) range and comprises 38 billion transitions between 7.3 million energy levels with rotational excitation up to J = 255. The NaOH OYT5 line list covers the 0 – 9000 cm−1 (wavelengths λ > 1.11 μm) range and contains almost 50 billion lines involving 7.9 million molecular states with rotational excitation up to J = 206. The OYT4 and OYT5 line lists are available from the ExoMol database at www.exomol.com and should greatly aid the study of hot rocky exoplanets.

scholarly journals ExoMol line list – XXXIV. A rovibrational line list for phosphinidene (PH) in its $X\, {}^3\Sigma ^-$ and $a\, {}^1\Delta$ electronic states

2019 ◽  
Vol 488 (2) ◽  
pp. 2332-2342 ◽  
Author(s):  
Jonathan Langleben ◽  
Jonathan Tennyson ◽  
Sergei N Yurchenko ◽  
Peter Bernath
Keyword(s):  
Ab Initio ◽  
Electronic States ◽  
Stellar Atmospheres ◽  
Spin Splitting ◽  
Mean Square ◽  
Data Bases ◽  
Line List ◽  
Line Intensities ◽  
Experimental Transition ◽  
Correction Terms

ABSTRACT A rovibronic line list for the ground (X 3Σ−) and first excited (a 1Δ) states of phosphinidene, 31PH, is computed. The line list is designed for studies of exoplanetary and cool stellar atmospheres with temperatures up to 4000 K. A combination of empirical and ab initio data is used to produce the line list: potential energy curves (PECs) are fitted using experimental transition frequencies; these transitions are reproduced with a root mean square error of 0.01 cm−1. The nuclear Schrödinger equation is solved using these PECs plus Born–Oppenheimer and spin splitting correction terms. Line intensities and Einstein   A coefficients are computed using ab initio dipole moment curves for X–X and a–a transitions. The resulting LaTY line list, which contains 65 055 transitions for 2528 rovibronic states up to 24 500 cm −1 and J = 80, is used to simulate spectra in emission and absorption for a range of temperatures. The line list is made available in electronic form at the CDS and ExoMol data bases.

scholarly journals Computation of Opacities for Diatomic Molecules

1994 ◽  
Vol 146 ◽  
pp. 282-295 ◽  
Author(s):  
Robert L. Kurucz
Keyword(s):  
Distribution Function ◽  
Least Squares ◽  
Diatomic Molecules ◽  
Energy Levels ◽  
Published Data ◽  
Molecular Line ◽  
Model Calculations ◽  
Line List ◽  
Thomas Fermi ◽  
Atomic Lines

In this section I briefly describe my efforts to improve the atomic and molecular line data. This work is described in more detail in Kurucz (1992a). In subsequent sections I briefly describe three methods for computing opacity and the models and spectra that result from using them.My model calculations in the 1970s used the distribution-function line opacity computed by Kurucz (1979a,b) from the line data of Kurucz & Peytremann (1975). We had computedgfvalues for 1.7 million atomic lines for sequences up through nickel using scaled-Thomas-Fermi-Dirac wavefunctions and eigenvectors determined from least squares Slater parameter fits to the observed energy levels. We also collected all published data ong fvalues and included them in the line list whenever they appeared to be more reliable than the computed data (that work is ongoing, but I am running behind).

scholarly journals On the relationship between molecular spectroscopy and statistical mechanics: Calculation of vibrational-rotational energy levels and partition functions in the ground electronic state of BC2

2011 ◽  
Vol 76 (4) ◽  
pp. 557-573 ◽  
Author(s):  
Milan Sencanski ◽  
Ljiljana Stojanovic ◽  
Stanka Jerosimic ◽  
Jelena Radic-Peric ◽  
Miljenko Peric
Keyword(s):  
Energy Spectrum ◽  
Ab Initio Calculations ◽  
Electronic State ◽  
Molecular Spectroscopy ◽  
Energy Levels ◽  
Rotational Energy ◽  
Ground Electronic State ◽  
Partition Functions ◽  
Bending Vibrations ◽  
The Relationship

The results of extensive ab initio calculations of the vibrational- rotational energy spectrum in the ground electronic state of the BC2 molecule are presented. These data were employed to discuss the evaluation of the corresponding partition functions. Special attention was paid to the problems connected with the calculation of the partition functions for the bending vibrations and rotations about the axis corresponding to the smallest moment of inertia.

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 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 Six-dimensional potential energy surface and rotation-vibration energy levels of HNCO in the ground electronic state

2019 ◽  
Vol 84 (8) ◽  
pp. 845-859
Author(s):  
Mirjana Mladenovic
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Electronic State ◽  
Energy Surface ◽  
Energy Levels ◽  
Ground Electronic State ◽  
Vibration Energy ◽  
Projection Scheme ◽  
State Mixing

A six-dimensional potential energy surface based on CCSD(T)/cc--pCVQZ ab initio energy points was developed for HNCO in the 1A??ground electronic state and used to calculate rotation?vibration energy levels for J?5. The barrier to linearity was computed to be 1834 cm-1 for the angle HNC and 336 cm-1 for the angle NCO. The fundamental transitions were obtained for the main form and four isotopic variants of HNCO. The state mixing v3/2v6 was identified with the help of an adiabatic projection scheme.

scholarly journals High-Temperature Collision Integrals for m-6-8 and Hulburt–Hirschfelder Potentials

2022 ◽  
Vol 43 (3) ◽  
Author(s):  
Marcin Buchowiecki
Keyword(s):  
High Temperature ◽  
Electronic State ◽  
Ground Electronic State ◽  
Quality Data ◽  
Lennard Jones Potential ◽  
High Quality ◽  
Collision Integrals ◽  
High Quality Data ◽  
Jones Potential ◽  
Lennard Jones

AbstractThis study is aimed to determine collision integrals for atoms interacting according to the m-6-8 and Hulburt–Hirschfelder potentials and analyze the differences between potentials. The precision of four significant digits was reached at all tested temperatures, and for high-temperature applications, six digits were calculated. The proposed method was tested on the Lennard-Jones potential and found to excellently agree with the recent high-quality data. In addition, the Hulburt–Hirschfelder potential was used for determining the collision integrals of the interaction of nitrogen atoms in the ground electronic state and compared with other known values. The calculations were performed using Mathematica computation system which can deal with singularities (so-called orbiting).

scholarly journals ExoMol line lists – XXXVIII. High-temperature molecular line list of silicon dioxide (SiO2)

2020 ◽  
Vol 495 (2) ◽  
pp. 1927-1933 ◽  
Author(s):  
A Owens ◽  
E K Conway ◽  
J Tennyson ◽  
S N Yurchenko
Keyword(s):  
High Temperature ◽  
Silicon Dioxide ◽  
Data Base ◽  
First Principles ◽  
Spectroscopic Data ◽  
Rotational Excitation ◽  
Molecular Line ◽  
Line List ◽  
Wavenumber Range

ABSTRACT Silicon dioxide (SiO2) is expected to occur in the atmospheres of hot rocky super-Earth exoplanets but a lack of spectroscopic data is hampering its possible detection. Here, we present the first, comprehensive molecular line list for SiO2. The line list, named OYT3, covers the wavenumber range 0 – 6000 cm−1 (wavelengths λ > 1.67 μm) and is suitable for temperatures up to T = 3000 K. Almost 33 billion transitions involving 5.69 million rotation–vibration states with rotational excitation up to J = 255 have been computed using robust first-principles methodologies. The OYT3 line list is available from the ExoMol data base at www.exomol.com.

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