Fateev, Alexander

Tennyson, Jonathan

Underwood, Daniel

Yurchenko, Sergei N.

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 20, 2017Variationally computed ro-vibrational energies of sulphur trioxideUnderwood, Daniel; Yurchenko, Sergei N.; Tennyson, Jonathan; Fateev, AlexanderPublication date:2012Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Underwood, D., Yurchenko, S. N., Tennyson, J., & Fateev, A. (2012). Variationally computed ro-vibrationalenergies of sulphur trioxide. Poster session presented at 22nd International Conference on High ResolutionMolecular Spectroscopy, Prague, Czech Republic.  IntroductionWe present preliminary results of a collaboration between academic and industrial efforts.We aim to create a high-temperaturespectroscopic database for SO3 which is essential in the analysis of complex data sets obtained through in situ measurements on industrial fuel units in power plants.Ultimately, the results will be used in working to:- increase the efficiency of electricity production by reducing NOx emissions;- optimising Ammonia consumption (Ammonia is used as a reductant);- reducing material corrosion and;- prolonging lifetimes of the selective catalytic reduction units.Atmospheric & Astronomical significance:SO3 is also a contributor to the formation of acid rain, and plays a significant role in atmospheric chemistry; it is also believed to be a constituent ofatmospheres in astronomical environments, such as Venus and Io [1].Variationally Computed Ro-Vibrational Energies of Sulphur TrioxideDaniel Underwood, Sergei N. Yurchenko, Jonathan Tennyson, Alexander FateevDepartment of Physics and Astronomy, University College London,Gower Street, LondonWC1E 6BTResultsFundamental Vibrations & Some Overtone/CombinationsPure Rotational EnergiesComparison of Reduced Energies (Ejk'- Ejk'') in 1550-1610cm-1 RegionExperimental [2] This Work Martin [3]v1 1064.924cm-1 1065.738cm-1 1064.219cm-1v2 497.567cm-1 498.475cm-1 487.100cm-1v3 1391.520cm-1 1387.428cm-1 1386.854cm-1v4 530.086cm-1 528.580cm-1 527.321cm-12v2 995.018cm-1 995.346cm-1 970.366cm-12v3(l=2) 2777.871cm-1 2769.954cm-1 2770.080cm-12v4(l=0) 1059.814cm-1 1056.440cm-1 1054.702cm-12v4(l=2) 1060.452cm-1 1057.332cm-1 1055.383cm-1v2 + v4 1027.902cm-1 1027.325cm-1 1013.453cm-1Computational Background and TROVE- Potential Energy Surface used in this work computed using MOLPRO.- Re-adjusted to an experimentally determined equilibrium bond length(1.41732 Angstroms [3]).- PES is then used by TROVE [4] to calculate ro-vibrational wavefunctions andenergy calculations.- For SO3 we define an active space such to maximise computational efficiency by the truncation of the Hamiltonian matrix blocks. This is basedon the following:●  Calculations of ro-vibrational energies up to and including 10,000cm-1;●  SO3 exhibits a polyad structure, and thus we can employ the polyadnumber [2]. We impose the condition on the quantum numbers that P = 2(v1 + v3) + v2 + v4 ≤ 14● Computational time is further reduced by noting that only energy levels ofA' and A'' symmetry are required.Next Step...- We aim to complete the current work by calculating all ro-vibrationalenergies up to J = 100. - To spectroscopically refine a new PES computed at the aug-cc-pVQZ-f12level of theory.- Calculations of an ab initio Dipole Moment Surface have already begun,using a aug-cc-pVTZ-f12 basis set, with preliminary intensity results fortransitions up to J = 20. We will eventually calculate intensities up to J = 100(T = 300K).References1) E. T.H. Chrysostom, N. Vulpanovici, T. Masiello, J. Barber, J. W. Nibler, A. Weber, A. Maki, T. A. Blake,“Coherent Raman and Infrared Studies of Sulphur Trioxide”, J. Mol. Spec., 210, 233-239 (2001)2) A. Maki, T. A. Blake, R. L. Sams, J. Frieh, J. Barber, T. Masiello, E. T.H. Chrysostom, J. W. Nibler, A. Weber,“Analysis of some combination-overtone infrared bands of 32S16O3”, J. Mol. Spec., 225, 109-122 (2004)3) Martin, J. M. L., “A fully ab initio quartic force field of spectroscopic quality for SO3”, Spectrochimica ActaPart A, 55, 105-112 (2002)4) S. N. Yurchenko, W. Thiel, P. Jensen, “Theoretical ROVibrational Energies (TROVE): A robust numericalApproach to the calculation of rovibrational energies for polyatomic molecules”, J. Mol. Spec., 245, 126-140(2007)AcknowledgementsThe projects are supported by the ERC grant (Advanced Investigator Project267219) and by Energinet.dk (Denmark, Project 10442).J K Experimental [2] This Work Difference2 0 2.091cm-1 2.091cm-1 0.0003cm-14 0 6.970cm-1 6.971cm-1 0.001cm-16 0 14.638cm-1 14.640cm-1 0.002cm-18 0 25.093cm-1 25.097cm-1 0.003cm-110 0 38.336cm-1 38.341cm-1 0.005cm-120 0 146.333cm-1 146.354cm-1 0.021cm-140 0 323.876cm-1 323.923cm-1 0.046cm-160 0 1271.537cm-1 1271.704cm-1 0.167cm-170 30 1569.767cm-1 1569.969cm-1 0.201cm-1The Molecule- A trigonal planar molecule that belongs tothe D point group.- Has 4 fundamental vibrational modes:● A' symmetric stretch● A'' out-of-plane bend● E' antisymmetric stretch● E' in-plane bendQuantum Numbers: J, K, v1, v2, v3l3, v4l4- Is composed entirely of spin-0 Bosons and therefore has only a single nuclear spin configuration and must exhibit anoverall symmetric wavefunction.- We therefore only have allowed ro-vibrational transitions between statesof A' and A'' symmetries.- SO3 is a relatively heavy molecule with a small rotational constant(B = 0.34854333(5)cm-1 [2]). Calculations of ro-vibrational energies up to high values of J are therefore necessary for large coverage in the production of synthetic spectra. A.Maki et al, reference [2] This workDepartment of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark0 12 24 36 48 6015501565158015951610v1 + v2 v2 +2v43v4E – BJ(J+1) + (C – B)K2JReduced Energy (cm-1)

Variationally computed ro-vibrational energies of sulphur trioxide

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Variationally computed ro-vibrational energies of sulphur trioxide

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