1. Theoretical work on the water monomer and dimer Matt Barber Jonathan Tennyson University College London matt@theory.phys.ucl.ac.uk December 2008

2. Outline of work so far Improvements to water line list Extended to cover 800-19,600 cm -1 New sources added Partition function for water dimer Few energy levels filled at low temperatures Most dimers are in the ground vibrational state Rotational levels convergent up to 20K No useful published comparisons

3. Line lists for 11000-19500 cm -1 HITRAN Good reference for strong lines BT2 R J Barber and Jonathan Tennyson, UCL Theoretical model with experimentally determined energy levels. Retrofitted experimental spectra Tolchenov R, Tennyson J: "Water line parameters from refitted spectra constrained by empirical upper state levels: study of the 9500-14500 cm-1 region". JQSRT, 109(4), 559-568 (2008). Grenoble data Very accurate measurements using cavity ring down spectroscopy Comparatively clean area for HITRAN lines

5. Line lists for 750-7500 cm -1 Coudert The H216O molecule: Line position and line intensity analyses up to the second triad, L.H. Coudert, G. Wagner, M. Birk, Yu.I. Baranov, W.J. Lafferty, J.-M. Flaud, JMS (preprint 2008) Brussels-Reims Fourier transform measurements of water vapor line parameters in the 4200-6600 cm-1 region, Jenouvrier, A; Daumont, L; Regalia-Jarlot, L, et al., JQSRT (105/2. pp 326- 355, 2007) Giessen Water vapor absorption line intensities in the 1900-6600 cm-1 region, Mikhailenko, SN; Albert, KAK; Mellau, G, et al., JQSRT (109/16, pp2687-2696, 2008) Grenoble Weak water absorption lines around 1.455 and 1.66 mu m by CW-CRDS, Mikhailenko, SN; Le, W; Kassi, S, et al., JMS (244/2, pp170-178, 2007)

10. Dimer partition function at 20K Only lowest vibrational state occupied Rotational states up to J=20 occupied Statistical weights g from Groenemboom et al. G 16 Symmetry Equation:

13. Conclusion Monomer linelist Now covering from Submit to BADC? Publish? Dimer partition function Convergent at 20K Reasonable at 50K Need many more levels for room temperature No low temperature comparisons available