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

2. Outline of work so far Improvements to water line list  Extended to cover 13,071-17,600 cm -1  Corrected to add some missing lines  Extend to infra-red? Water monomer band intensities  To approximate water dimer spectrum  Can be built from monomer dipole surface Partition function for water dimer  Few energy levels filled at low temperatures

3. Line lists 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. H 2 O monomer band intensities Fits into Franck-Condon approximation Only considering vibrational transitions  Only one excited monomer  Two leads to dissociation CVR potential surface  Lodi L, Tolchenov R, Tennyson J, Lynas-Gray AE, Shirin SV, Zobov N, Polyansky OL, Csaszar AG, van Stralen JNP, Visscher L.: "A new ab initio ground state dipole moment surface for the water molecule". J. Chem. Phys., in press.  Valence-only (V) dipole with core (C) and relativistic (R) corrections Test for consistency against publications  HITRAN 1994  Jorgensen & Jensen (1993)‏

8. Dimer partition function at 20K Only lowest vibrational state occupied Statistical weights from Groenemboom et al.  G 16 Symmetry Need rotational energy levels  Ross is working on this Equation:

9. Conclusion Monomer linelist  Extend to infra-red? Monomer band intensities  In progress Dimer partition function  20K soon  300K eventually  Anything else in between?