Generating a canonical change with F₂
A smooth type-2 generating function F₂(q,P,t) defines p_i=∂F₂/∂q_i and Q_i=∂F₂/∂P_i.
Key knowledge
A smooth type-2 generating function F₂(q,P,t) defines p_i=∂F₂/∂q_i and Q_i=∂F₂/∂P_i. If the old/new variables can be locally inverted, the new Hamiltonian is K=H+∂F₂/∂t, expressed in the new variables.
Values and equations
p_i=∂F₂/∂q_i; Q_i=∂F₂/∂P_i; K=H+∂F₂/∂t
- F₂
- Type-2 generating function J s
- q_i,Q_i
- Old/new generalized coordinates with their own units
- p_i,P_i
- Old/new momenta; coordinate–momentum product has unit J s
- H,K
- Old/new Hamiltonians J
- t
- Time s
Conditions and scope
- Regular finite-dimensional Hamiltonian mechanics with a nondegenerate mixed derivative needed for the local inverse.
- Not every generating function chart covers an entire trajectory or global phase space.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Classical Mechanics III 8.09 (2014): Chapter 4: §4.1 printed pages 62–63, equations 4.23–4.29: type-2 generating function and time correction.
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Entry details
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