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Basics of classical GCM Lagrangian 5 coordinates 5 velocities
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Classical Chaos in
Geometric Collective Model
Pavel Stránský, Pavel Cejnar, Matúš Kurian
Institute of Particle and Nuclear PhycicsFaculty of Mathematics and PhysicsCharles University in Prague, Czech Republic
1. Classical GCM and its dynamics2. Scaling properties3. Angular momentum and equations of
motion4. Poincaré sections and measure of chaos5. Numerical results for 6. Numerical results for
0J
Outline
0zJ
J
Basics of classical GCMLagrangian VTL
5 coordinates5 velocities
Scaling propertiesof Lagrangian
General Lagrangian:
transformation of 3 fundamental physical units:
size (deformation)energy (Lagrangian)time
Important example:
Introduction of angular momentum
Spherical tensor of rank 1:
Spherical symmetry of the Lagrangian – angular momentum is conserved.
2 special cases:0zJ
In Cartesian frame (Jx, Jy, Jz) we choose rotational axis paralel with z +
Nonrotating case
0J
Nonzero variables:
New coordinatesWell-known Bohr coordinates:
Generalization:
In this new coordinates kinetic and potential terms in Lagrangian reads asand angular momentum
Solution of the Lagrangeequation of motion
How to use these trajectories
to clasify the system?
Measures of Chaos1. Lyapunov exponent (for a trajectory in the phase space):• positive for chaotic trajectories• slow convergence
Deviation of two neighbouring trajectories in phase space
2. Poincaré sections, surface of the sections3. SALI (Smaller Alignment Index)
• reach zero for chaotic trajectories• fast convergence
Ch. Skokos, J. Phys. A: Math. Gen 34 (2001), 10029; 37 (2004), 6269
Poincaré sections
Poincaré sections
- surface
For this example (GCM with A = -5.05,
E = 0, J = 0)
freg=0.611
Poincaré sectionsFor systems with trajectories laying on 4- or higher-
dimensional manifolds (practically systems with more than 2 degrees of freedom)IT IS NOT POSSIBLEto use surface of sections to measure quantity of chaos
Fishgraph A = -2.6, E = 24.4
Results for J = 0(using Poincaré
sections)
A = -0.84
Dependence of freg on energy
Dependence of freg on energy
• full regularity for E near global minimum of potential • complex behaviour in the intermediate domain• sharp peak for E = 23 if A > -0.8• logaritmic fading of chaos for large E
• for B = 0 system is integrable -> fully regular• for small B chaos increases linearly, but the increase stops earlier than freg = 0• for very large B system becomes regular
Dependence of freg on B (on A) for E = 0
Results for 0zJ(using Lyapunov exponents)
Noncrossing ruleQuadrupole deformation tensor in Cartesian (x, y, z) components
Difference of the eigenvalues
It can be zero only if Jz = 0.
Increasing j
Summary
1. There is only 1 essential external parameter in our truncated form of GCM
2. GCM exhibits complex interplay between regular and chaotic types of motions depending on the control parameter A and energy E
3. Poincaré sections are good tools to quantify regularity of classical 2D system
4. The effect of spin cannot be treated in a perturbative way5. With increasing J the system overall tend to suppress the
chaos for small B and to enhance it for large B6. SALI method could be succesfuly used to analyse efects of
general spin
Thank you for your attention