0000000000383002
AUTHOR
Ch. Wenger
top data system ( TDS) software for infrared spectrum simulation of asymmetric molecules: some improvements to the TDS packages
Abstract The spherical top data system (STDS) program suite developed in Dijon has been extended with the aim of studying any rovibrational band or polyad of XY 2 Z 2 ( C 2 v ) asymmetric top molecules. We work in the O ( 3 ) ⊃ T d ⊃ C 2 v chain because these species result from the substitution of two ligands of a corresponding “parent” spherical top and thus are relatively close to tetrahedral symmetry. The choice of this group chain has consequences on the method used to specify the input parameters of the programs for Hamiltonian and transition moment model calculations. One example concerning the ground state of the SO2F2 quasi-spherical molecule is presented. As before, this suite con…
The partition sum of methane at high temperature
11 pages, 4 Tables, 3 Figures Computer code on line at http://icb.u-bourgogne.fr/JSP/TIPS.jsp; International audience; The total internal partition function of methane is revisited to provide reliable values at high temperature. A multi-resolution approach is used to perform a direct summation over all the rovibrational energy levels up to the dissociation limit. A computer code is executable on line at the URL : http://icb.u-bourgogne.fr/JSP/TIPS.jsp to allow the calculation of the partition sum of methane at temperatures up to 3000 K. It also provides detailed information on the density of states in the relevant spectral ranges. The recommended values include uncertainty estimates. It is …
Symmetry-adapted tensorial formalism to model rovibrational and rovibronic spectra of molecules pertaining to various point groups
International audience; We present a short review on the tensorial formalism developed by the Dijon group to solve molecular spectroscopy problems. This approach, originally devoted to the rovibrational spectroscopy of highly symmetrical species (spherical tops) has been recently extended in several directions: quasi-spherical tops, some symmetric and asymmetric tops, and rovibronic spectroscopy of spherical tops in a degenerate electronic state. Despite its apparent complexity (heavy notations, quite complex mathematical tools), these group theoretical tensorial methods have a great advantage of flexibility: a systematic expansion of effective terms for any rovib- rational/rovibronic probl…
D2hTDS-ST Software for Stark Spectrum Simulation of X2Y4 Asymmetric-Top Molecules
Abstract We present the D 2 h TDS-ST ( D 2 h -Top Data System for Stark effect) program suite with the aim to simulate Stark spectra of any IR active rovibrational polyad of X 2 Y 4 ( D 2 h ) asymmetric-top molecules. D 2 h TDS-ST consists in a series of FORTRAN programs called by scripts. For calculation of Stark spectra, we obtained the expressions of the dipole moment and polarizability operators of X 2 Y 4 molecules using a tensorial formalism. For convenience, we integrated the D 2 h TDS-ST programs into the D 2 h TDS package. The D 2 h TDS suite (including the D 2 h TDS-ST programs) is freely available at the URL: http://icb.u-bourgogne.fr/OMR/SMA/SHTDS/D2HTDS.html .
Spectroscopic tools for remote sensing of greenhouse gases CH4, CF4 and SF6
International audience; Highly symmetrical molecules such as CH4, CF4 or SF6 are known to be atmospheric pollutants and greenhouse gases. High-resolution spectroscopy in the infrared is particularly suitable for the monitoring of gas concentration and radiative transfers in the earth's atmosphere. This technique requires extensive theoretical studies for the modeling of the spectra of such molecules (positions, intensities and shapes of absorption lines). Here, we have developed powerful tools for the analysis and the simulation of absorption spectra of highly symmetrical molecules. These tools have been implemented in the spherical top data system (STDS) and highly-spherical top data syste…
Towards simulation of high temperature methane spectra
Methane plays a central role in gas layers of temperatures up to around 3000 K in a number of astrophysical objects ranging from giant planets to brown dwarfs, over proto-solar nebulae, to several classes of cool stars. In order to model and analyse these objects correctly, an accurate and complete list of spectral lines at high temperature is demanded. Predicting high temperature spectra implies, however, predicting hot bands and thus modelling highly excited vibrational states. This is a real challenge in the case of methane. We report the preliminary results of a theoretical study combining the global effective Hamiltonian approach and its computational implementation (STDS package: http…
Multi-Resolution error analysis of predicted absorption coefficients. Method and application to the infrared spectrum of methane at high temperature.
La version V2 inclut les modifications proposées par les reviewers.; International audience; A general method for the estimation of the confidence interval of molecular absorption coefficients is presented. Statistical numerical experiments are implemented to quantify the propagation of errors from line parameters to absorption coefficients or cross-sections as a function of the resolution. The method uses line parameter predictions (position and intensity) with estimated uncertainties derived from global polyad models. This work is especially intended to provide expert information for applications requiring theoretical predictions for which the present state of the art of line by line high…
Highly-spherical Top Data System (HTDS) software for spectrum simulation of octahedral XY6 molecules
Abstract The Spherical Top Data System (STDS) program suite developed in Dijon has been extended into two directions. First, the vibrational extrapolation is now possible for any kind of polyad scheme, this one being fully specified in the input parameters of the programs for hamiltonian and transition moment model calculations. This was not the case of the preceding version which was based on the polyad scheme of methane. Secondly, it is now possible to study any band and polyad of XY 6 molecule for which a complete treatment in the O h group is made. Up to now, only some vibrational levels of these molecules ( F 1u levels in particular) could be studied using equivalences with the T d gro…
C3v Top Data System (C3vTDS) software for spectrum simulation of XY3Z symmetric-top molecules using the group chain
Abstract The C3v Top Data System (C3vTDS) program suite has been developed with the aim of studying any rovibrational band or polyad of XY3Z (C3v) symmetric-tops molecules in a singlet electronic state. It is developed in the same way as similar programs for various molecular symmetries (Td, Oh, C4v, C2v and D2h). We work in the O ( 3 ) ⊃ C ∞ v ⊃ C 3 v group chain and this choice has consequences on the method used to specify the input parameters for Hamiltonian and transition moment calculations. One example concerning the ν 2 band of the CH 3 12 D symmetric-top molecule is presented. This package consists in a series of FORTRAN programs called by scripts. The whole package is freely acces…
Spherical top data system (STDS) software for the simulation of spherical top spectra
Abstract The Spherical Top Data System (STDS) software package for the simulation of spherical top spectra is presented. It consists of a single UNIX script with self-explanatory arguments allowing the non-expert user to calculate spectra from the results of the high resolution analyses performed over the recent decades on this type of molecules. More than one hundred parameter files are presently available including various band systems of 16 molecular species (among which methane is the most documented) and various types of calculations: rovibrational energy levels, i.r. absorption, Raman scattering and Stark coefficients. STDS is freely accessible by anonymous ftp at jupiter.u-bourgogne.…
C4v Top Data System (C4v TDS) software for infrared spectrum simulation of XY5Z symmetric molecules
Abstract The Highly spherical Top Data System program suite developed in Dijon has been extended in the aim of studying any rovibrational band or polyad of XY5Z (C4v) symmetric top molecules. We work in the O(3)⊃Oh⊃C4v chain because most of these species result from the substitution of one ligand of the corresponding spherical tops and thus are relatively close to octahedral symmetry. The choice of this group chain has consequences in the way in which it is used to specify the input parameters of the programs for Hamiltonian and transition moment model calculations. One example concerning the ν1/ν8 dyad of the SF 5 35 Cl molecule is presented. As before, this suite consists of a series of F…
Orientation of O(3) and SU(2)⊗CI representations in cubic point groups (Oh,Td) for application to molecular spectroscopy
Abstract We propose a detailed method for the symmetrization of the standard O (3) or SU (2)⊗ C I basis | j τ , m 〉 ( τ = g or u ) into the O h or T d point group. This is realized by means of an orientation matrix called G . The oriented basis obtained in this way allows matrix element calculations for rovibronic spectroscopic problems concerning octahedral or tetrahedral molecules. Particular attention has been put on careful phase choices. A numerical calculation of all the G matrix elements for both integer and half-integer j values up to 399/2 has been performed. Such high angular momentum values are necessary for the case of heavy molecules with high rotational excitation. To calculat…
top data system (TDS) software for spectrum simulation of asymmetric molecules
Abstract The D 2 h TDS ( D 2 h Top Data System) program suite has been developed with the aim of studying any rovibrational band or polyad of X 2 Y 4 ( D 2 h ) asymmetric top molecules. It is based on the same principles as similar programs from our group already released for various molecular symmetries ( T d , O h , C 4 v , C 2 v ). We work in the O ( 3 ) ⊃ D 2 h chain and this choice has consequences on the method used to specify the input parameters of the programs for Hamiltonian and transition moment calculations. Two examples concerning the ν 12 and ν 2 bands of the C 2 H 4 molecule are presented. This suite consists of a series of FORTRAN programs called by a script. The whole packa…
Methane line parameters in the HITRAN2012 database
International audience; The compilation of methane molecular line parameters was updated to include new global analyses and measurements for 12CH4, 13CH4 and 12CH3D. Over 70% of the methane parameters in HITRAN2008 were replaced; existing parameters retained were the microwave lines and the Dyad of 13CH4 near 7 μm and ν6 of 13CH3D near 8.7 μm, 12CH3D (7-4076 cm-1), hot bands of 12CH4 (1887-3370 cm-1) and normal sample CH4 (4800-5550 cm-1 and 8000-9200 cm-1). With a minimum intensity at 296 K in units of cm-1/(molecule cm-2) set to 10-37 for the far-IR and 10-29 for the mid- and near-IR, the methane database increased from 290,091 lines in HITRAN2008 to 468,013 lines, and three-fourths of th…
High resolution spectroscopy and the first global analysis of the Tetradecad region of methane 12CH4.
We present the first detailed analysis of the infrared spectrum of methane (12)CH4 in the so-called Tetradecad region from 2.1 to 1.6 μm (4760-6250 cm(-1)). New experimental high resolution FTIR spectra at 78 K and at room temperature combined with improved theoretical modeling have allowed quantum assignments to be greatly extended in this region. A global fit of all assigned lines of (12)CH4 in the 0-6200 cm(-1) region has been performed. In the end, 3012 line positions and 1387 intensities of 45 individual subbands of the Tetradecad were modeled up to J = 14. The root mean square deviations were 0.023 cm(-1) for line positions and 13.86% for line intensities in the Tetradecad region itse…
New assignments in the 2μm transparency window of the 12CH4 Octad band system
Abstract This paper reports new assignments of rovibrational transitions of 12 CH 4 bands in the range 4600–4887 cm −1 which is usually referred to as a part of the 2 μm methane transparency window. Several experimental data sources for methane line positions and intensities were combined for this analysis. Three long path Fourier transform spectra newly recorded in Reims with 1603 m absorption path length and pressures of 1, 7 and 34 hPa for samples of natural abundance CH 4 provided new measurements of 12 CH 4 lines. Older spectra for 13 CH 4 (90% purity) from JPL with 73 m absorption path length were used to identify the corresponding lines. Most of the lines in this region belong to th…