Prof. Jonathan Tennyson,
University College London,
Chair, IUPAC task group "A database of water transitions from experiment and theory"
The University College London (UCL) team has pioneered the use of variational calculations for high accuracy calculations on the rotation-vibration states of triatomic molecules. This method and the team's programs are used worldwide. In particular the team introduced of a two-step variational technique for treating rotationally excited states which has allowed realistic spectra to be synthesized and is the key to successes discussed below and to the present proposal.
The team successfully used first principles quantum mechanical calculations to assign an emission spectrum of H3+ in the Jovian ionosphere. This led to a new observational handle on Jupiter and other gas giants and has yielded many significant new insights about the ionospheres of these objects. Observations and models of H3+ in gas giants have become a major research activity which is vigorously pursued at UCL and in several groups elsewhere.
Use of variational calculations to analyze rotation-vibration spectra led to a major break-through in the theory of water spectra with the assignment of an absorption spectrum in sunspots. The method has been successfully applied to spectra of hot water, which is rotationally highly excited, and short wavelength spectra, where water is highly vibrationally excited. Use of this work in collaboration with experiments led to the identification of an extra 8 to 10 W/m2 absorption of sunlight in our atmosphere by water vapour. The team is involved with astrophysical observations of water spectra in the atmospheres of cool stars and collaborates extensively with atmospheric physicists involved in both global models of the earth's radiation budget and the analysis remote sensing obtained from ESA satellites.
Recently the team has developed high accuracy procedures for predicting spectra. These procedures are based on two on two complimentary methods (a) fitting potentials to spectroscopic data or (b) the use ab initio electronic structure calculations. The team, in collaboration with those at ELTE and IAP, have demonstrated that first principles calculations approaching spectroscopic accuracy cam be achieved but require both large and sophisticated electronic calculations, extrapolation of results and inclusion of effects due relativity, quantum electrodynamics and failure of the Born-Oppenheimer approximation.
The team receives significant funding from UK research councils and currently holds grants from EPSRC (3), NERC and PPARC. It also participates in 3 European Union networks, one of which is devoted to molecular spectroscopy and involves UNIFJG. UCL has had long-running and very successful collaborations with both the IAP and ELTE teams.
The team has a cluster of Linux PC and a new 32 processor, 132 Gb memory Sunfire machine for in house computing. The team leader chairs the UK high performance computing consortium ChemReact which has over 8 millions hours on the UK's new hpcx supercomputer.
List of publications
1. O.L. Polyansky, A.G. Csaszar, S.V. Shirin, N.F. Zobov, P. Barletta, J. Tennyson, D.W. Schwenke, P.J. Knowles, High accuracy ab initio rotation-vibration transitions of water, Science, 299, 539-542 (2003).
2. A. Callegari, P. Theule, R.N. Tolchenov, N.F. Zobov, O.L. Polyansky, J. Tennyson, J.S. Muenter, T.R. Rizzo, Dipole moments of highly vibrationally excited water, Science, 297, 993-995 (2002).
3. J.Tennyson, N.F.Zobov, R.Williamson, O.L.Polyansky, P.F.Bernath, Experimental energy levels of the water molecule, Journal of Physical and Chemical Reference Data, 30, 735-831 (2001).
4. K.Tereszchuk, P.F.Bernath, N.F.Zobov, S.V.Shirin, O.L.Polyansky, N.I.Libeskind, J.Tennyson, L.Wallace, Laboratory Spectroscopy of Hot Water Near 2-Microns and Sunspot Spectroscopy in the H-Band Region, The Astrophysical Journal, v.577, 496-500 (2002).
5. W.Zhong, J.D.Haigh, D.Belmiloud, R.Schermaul, J.Tennyson, The impact of new water vapour spectral line paramaters on the calculation of atmopsheric absorption, Quart. J. Royal Meteorol. Soc., v.127, 1615-1626 (2001).