Nonadiabatic Dynamics

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Nonadiabatic Dynamics

• Ke-Li Han
• State Key Laboratory of Molecular Reaction
  Dynamics, Dalian Institute of Chemical Physics,
  Chinese Academy of Sciences

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Outline

• Theoretical studies Nonadiabatic Quantum
  dynamics of F(2P3/2,2P1/2)HD, Cl(2P3/2,
  2P1/2)H2, O(3P,1D)H2 using time-dependent
  wavepacket method
• Experimental studies Direct measurement of the
  conversion time from the Sn(n2,3,4) to the S1
  states of Chlorophyll a by using femtosecond
  laser in solution

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The spin-orbit effect for nonadiabatic F(2P3/2,
2P1/2) H2 /DH reaction

• Since Lee and coworkers work in 1985, the
  reaction FH2 has been as a case example of
  textbook for molecular reaction dynamics
• Recently Kopin Liu and coworkers have found that
  a resonant peak appears in the integral cross
  section for the reactive channel of FHD?HFD
  experimentally
• Skodje and coworkers have done the quantum
  scattering calculations on Stark and Werner (SW)
  PES.

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Alexander, Stark, and Werner fitted new coupled
PESs (named as ASW PESs) published in J. Chem.
Phys. 113 (2000) 11084.
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Research approach

• Improvement of the three-dimensional
  time-dependent wavepacket method
• Develop an extended split operator
  scheme(XSOS) to propagate the quantum wavepacket
• A Fortran code embodied the XSOS

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Basis Function
Kk?s
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Probabilities calculated on the two PESs and six
PESs for the reaction of F(2P1/2) with H2 (vj0)
as a function of the translation energy for
J0.5. the dotted line is for the
time-independent result(Ref.24).
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TDWP nonadiabatic calculation for the FHD
reaction on ASW surfaces
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TDWP nonadiabatic calculation for the FHD
reaction on ASW surface
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Modified ASW potential energy surfaces (MASW PESs)

• The barrier height of ASW potential energy
  surfaces is lowered by 0.016eV for the lowest
  barrier at the bent configuration and lowered by
  0.015eV for the collinear with the scale external
  correlation technique, developed by Truhlar and
  coworkers

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FHD?HFD
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FHD?DFH
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Cl(2P3/2)?Cl(2P1/2)H2
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????
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The time-independent calculations were carried
out on Capecchi and Werner (CW) diabatic PESs
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We have re-fitted the diabatic coupled surfaces
for ClH2, named as Xie and Han (XH) PESs
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The integral cross sections for the reaction ClH2
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Conclusions

• The calculated cross sections on modified ASW
  PESs are much closer to experimental results than
  those on ASW PESs for FHD
• The calculated cross sections of the SO excited
  state on XH PESs are much higher than those on CW
  PESs for ClH2. We are confirming those results.

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Time-dependent wavepacket study of the
intersystem crossing effects in O(3P,1D)H2
reaction

• An exact quantum scattering calculation

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About O(3P,1D)H2 reaction

• Prolific dynamics information
• Most investigated reaction system
• Research interests
• single PES problems
• abstraction/insertion mechanism et al.
  
• multi-PES problems
• role of excited surface
• role of spin-orbit induced transition

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Why do this quantum calculation?

• Intersystem crossing is important in many
  reaction systems such as enzymatic reaction,
  surface induced collision and dissociation et al.
• Very few theoretical work, no quantum study so
  far
• Schatz and coworkers TSH method
• Challenges are daunting difficult to perform
  exact quantum scattering calculation for such
  issue.

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Challenges

• Too many electronic states coupled in the
  intersystem crossing
• A feasible quantum dynamics method to treat this
  multi-surface problem
• The deep singlet state potential well about 7.9
  eV in the reaction system

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A schematic profile of singlet-triplet crossing
in O(3P,1D)H2 reaction
Schatz and coworkers
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Results of the quantum calculations (1)
Cross section with wavepacket initially in 3P2
state
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Results of the quantum calculations (2)
Cross section with wavepacket initially in 3P2
state
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Results of the quantum calculations (3)
Cross section with wavepacket initially in 3P1
state
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Results of the quantum calculations (4)
Cross section with wavepacket initially in 3P1
state
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Results of the quantum calculations (5)
Cross section with wavepacket initially in 3P0
state
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Results of the quantum calculations (6)
Cross section with wavepacket initially in 3P0
state
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Results of the quantum calculations (7)
Cross section with wavepacket initially in 1D2
state
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Results of the quantum calculations (8)
Cross section with wavepacket initially in 1D2
state
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A comparison between the previous TSH study and
the present quantum study (1)
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A comparison between the previous TSH study and
the present quantum study (2)
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Conclusion remark

• The spin-orbit coupling between triplet states of
  different symmetry, such as 3A and 3A, plays a
  significant role in the singlet-triplet crossing
  process.
• A branch ratio of product OH spin state ?3/2 to
  ?1/2 is calculated to be around 2.75 1 at high
  collision energy, which is in rough agreement
  with the measured OH ratio of 21 in the reaction
  of O(3P2,1,0) with hydrocarbon.

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Nonadiabatic quantum dynamics studies of other
systems

• Nonadiabatic Dynamics of Energy Transfer Process
  electronic quenching process O(1D)
  N2(X1Sg) ?O(3P) N2(X1Sg)
• Nonadiabatic Dynamics of Charge Transfer
  DH2?DH2
• Nonadiabatic Photodissociation H2O, CH3I

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Collaborators

• Ting-Xian Xie
• Yan Zhang
• Tian-Shu Chu
• Xin Zhang
• John Zhang