Slide 1

Conical Intersections between Vibrationally Adiabatic Surfaces in Methanol Mahesh B. Dawadi and David S. Perry Department of Chemistry, The University of Akron, Akron OH 44325 Acknowledgements Slide 2 Born-Oppenheimer approximation: - Adiabatic separation of electronic and nuclear motion Jahn-Teller effect and E e conical intersection Zwanziger and Grant E e formalism: C 3V symmetry JT scaling linearly plus Renner-Teller scaling quadratically vs distortion A set of 4 conical intersections Vibrational adiabatic approximation: Methanol Xu et al: CH stretches as a function of Both Jahn-Teller and Renner-Teller couplings No -dependence Vibrational conical intersections Ultrafast vibrational relaxation Introduction R.G. McKinlay, J.M. Zurek, M.J. Paterson, Adv. Inorg. Chem. 62, 351 (2010). J. W. Zwanziger and E. R. Grant, J. Chem. Phys. 87, 2954 (1987). L.-H. Xu, J.T. Hougen, R.M. Lees, J. Mol. Spectrosc. 293-294, 38 (2013). P. Hamm and G. Stock, Phys. Rev. Lett. 109, 173201 (2012). 2 Slide 3 Conical Intersections between Vibrationally Adiabatic Surfaces in Methanol 3 Slide 4 Ab initio Levels: MP2/6-311+G(3df,2p) Staggered Eclipsed Methanol Asymmetric CH-Stretch Frequencies Global Minimum Torsional Saddle Conical intersections (CIs) =93.6 = 61.9 Eclipsed-CI = 0 C 3v geometry = 60, 180, 300 = 0, 120, 240 4 Slide 5 Methanol Asymmetric CH-Stretches: Frequencies and Force constants Ab initio Levels: MP2/6-311+G(3df,2p) B3LYP/6-31+G(2d,p) 5 Slide 6 Computed Points and Conical Intersections CIs Staggered Eclipsed Global Minimum Torsional Saddle = 60, 180, 300 = 0, 120, 240 =93.6 = 61.9 Eclipsed-CI = 0 C 3v geometry 6 Slide 7 Computed Frequencies Along the Torsional MEP Table 5 of L.-H. Xu, J.T. Hougen, J.M. Fisher, R.M. Lees, J. Mol. Spectrosc. 260, 88 (2010). Fig.9. of L.-H. Xu, J.T. Hougen, R.M. Lees, J. Mol. Spectrosc. 293-294, 38 (2013). 22 99 Torsional saddle Global minimum 7 Slide 8 Model Calculation 8 Slide 9 and eigenvalues in wavenumber: L.-H. Xu, J.T. Hougen, R.M. Lees, J. Mol. Spectrosc. 293-294, 38 (2013). J. W. Zwanziger and E. R. Grant, J. Chem. Phys. 87, 2954 (1987). Extension of Zwanziger and Grant model to large distortion angle, 9 Slide 10 -Dependent Model Parameters Polynomial expansions in Fit of data points (C s -symmetry) Staggered Eclipsed Fit rms of 0.9 cm -1 for All 318 ab intio points for Cs and non-Cs geometries 10 Slide 11 11 Slide 12 A Seam of Conical Intersections 12 Slide 13 A Seam in 3-D: r CO, , CIs at = 61.9 and 93.6 belong to same seam of CIs r CO Eclipsed methanol, =0 13 Slide 14 Conclusions 7 conical intersections found in methanol accessible at low energies become seams in 3-D and higher Implications for spectroscopy a test of the adiabatic concept level patterns in torsionally excited states states with mixed geometric phase Implications for dynamics localized ultrafast energy transfer P. Hamm and G. Stock, Phys. Rev. Lett. 109, 173201 (2012). 14 Slide 15 Thank you Questions or Comments? 15 Slide 16 Computed Frequencies Along The MEP Table 5 of L.-H. Xu, J.T. Hougen, J.M. Fisher, R.M. Lees, J. Mol. Spectrosc. 260, 88 (2010) Fig.9. of L.-H. Xu, J.T. Hougen, R.M. Lees, J. Mol. Spectrosc. 293-294, 38-59 (2013) New model XHL model 22 99 16 Slide 17 17 Slide 18 18 Slide 19 19 Slide 20 20 Slide 21 21