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The Landau-Teller model revisited
Tim Wendler and Manuel Berrondo BYU Physics
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Quantum-Classical coupling Lie algebraic solution 6 coupled equations
I am calculating the dynamics of a collinear atom/diatomic molecule inelastic collision Jacobi coordinates Quantum-Classical coupling Lie algebraic solution 6 coupled equations Canonical ensemble
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Collinear Configuration
Diatomic molecule Atom Harmonic oscillator potential for BC Repulsive interaction for AB No AC interaction Energy is in units of Valid for
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Jacobi Coordinates 1 2
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Potential Energy Surface
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Equations of motion Classical for Translation Quantum for vibration
Expansion Classical for Translation Quantum for vibration
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Expanded and Rearranged
Quantum Hamiltonian “dipole” term Expanded and Rearranged Quantum for vibration
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Time Evolution Operator
Constant ket Quantum equation of motion for vibration
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Lie Algebraic Approach
Time dependence goes into “c” numbers
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Nuances End up with terms like Utilize Berrondo anti-symmetric product
Very general and useful equation End up with terms like Utilize Berrondo anti-symmetric product
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Not operator equations!
6 coupled equations Not operator equations!
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Transition Rates Initial conditions
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Phase Space Calculations
Initial conditions
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Intuitive plot of collision
New Trajectory
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Classical Comparison Quantum phase gained energy Classical phase lost energy Same until initial speed passes the max oscillator speed Certain phase relations result in opposite effects
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A density matrix can represent a statistical mixture of pure states.
Mixed States A superposition is in both states A mixture is in perhaps one or perhaps the other No interference A density matrix can represent a statistical mixture of pure states.
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Quantum Liouville Equation
Initial state in equilibrium at temperature T Just after the collision In principle, isolated quantum systems are very non-ergodic, and one must couple them to the outside world to induce transitions between the many-body Eigenstates needed for equilibrium.
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Out of equilibrium, for the moment
A canonical ensemble of oscillators Non-equilibrium Initial State of canonical ensemble at Temperature T Just after collision, thermal equilibrium is lost
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General boson algebra coefficients already calculated!
Summary No wave functions A simple equation standard Phase Space Transition Rates Canonical Ensemble Infinite order transitions Specific system input General boson algebra coefficients already calculated!
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Oxidation of methyl esters
Future – Reactive Collisions SN2 Reactions Nuclear Reactions Oxidation of methyl esters
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