Vibrationally Adiabatic Surfaces in Methanol Mahesh B Dawadi and David S Perry Department of Chemistry The University of Akron Akron OH 44325 Acknowledgements BornOppenheimer approximation ID: 272426
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Slide1
Conical Intersections between
Vibrationally
Adiabatic Surfaces in Methanol
Mahesh B. Dawadi and David S. PerryDepartment of Chemistry, The University of Akron, Akron OH 44325
AcknowledgementsSlide2
Born-Oppenheimer approximation:
- Adiabatic separation of electronic and nuclear motionJahn-Teller effect and
E⊗e conical intersectionZwanziger and Grant E⊗e formalism: C
3V symmetryJT scaling linearly plus
Renner-Teller scaling quadratically vs distortion
ρ
A set of 4 conical intersectionsVibrational adiabatic approximation: Methanol Xu et al: CH stretches as a function of γ Both Jahn-Teller and Renner-Teller couplings No ρ-dependenceVibrational conical intersectionsUltrafast 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).
2Slide3
Conical Intersections
between Vibrationally Adiabatic Surfaces in Methanol
3Slide4
Ab
initio
Levels: MP2/6-311+G(3df,2p)
StaggeredEclipsedMethanol
Asymmetric CH-Stretch FrequenciesGlobal Minimum
Torsional SaddleConical intersections (CIs)
ρ
=93.6° ρ = 61.9°
Eclipsed-CI
Eclipsed-CI ρ = 0°C3v geometryγ = 60˚, 180˚, 300˚ γ = 0˚, 120˚, 240˚
4Slide5
Methanol
Asymmetric CH-Stretches:
Frequencies and Force constants
Ab initio Levels: MP2/6-311+G(3df,2p) B3LYP/6-31+G(2d,p)
5Slide6
Computed Points and Conical Intersections
CIs
Staggered
Eclipsed
Global Minimum
Torsional Saddleγ = 60˚, 180˚, 300˚
γ
= 0˚, 120˚, 240˚ ρ =93.6° ρ = 61.9°
Eclipsed-CI
Eclipsed-CI ρ = 0°C3v geometry
6Slide7
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).
ν
2ν9
Torsional saddle
Global minimum7Slide8
Model Calculation
8Slide9
Model Calculation
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, ρ 9Slide10
ρ
-Dependent Model Parameters
Polynomial expansions in
ρFit of data points (Cs
-symmetry)
Staggered
Eclipsed
Fit rms of 0.9 cm-1 for All 318 ab intio points for Cs and non-Cs geometries 10Slide11
11Slide12
A Seam of Conical Intersections
12Slide13
A Seam in 3-D:
rCO
, ρ, γ
CIs at ρ = 61.9˚ and 93.6˚ belong to same seam of CIs
rCO
Eclipsed methanol,
γ
=0˚13Slide14
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).14Slide15
Thank you
Questions or Comments?
15Slide16
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
ν
2ν916Slide17
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