Whereas model constraints (e.g., frozen bonds, fixed bending or torsonial angles, rigid atomic groups, etc.) are often imposed in calculations of the potential energies of polyatomic molecules by quantum-chemical methods. the derivation of exact expressions for the corresponding kinetic energy opera
Hamiltonians for constrained N-particle systems
β Scribed by A. Nauts; X. Chapuisat
- Publisher
- Elsevier Science
- Year
- 1987
- Tongue
- English
- Weight
- 515 KB
- Volume
- 136
- Category
- Article
- ISSN
- 0009-2614
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β¦ Synopsis
The efficiency of the theoretical methods to obtain exact expressions of classical and quantum-mechanical Hamiltonians for N-particle systems described in terms of curvilinear coordinates (q), is shown to depend strongly on whether the system is subjected to constraints or not. If it is free, the method based upon the use of the relations q = q(x), where x denotes moving-frame Cartesian coordinates of the particles, is preferable. If it is constrained, the method making use of x = x(q) can become more efficient.
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We derive an algorithm for the construction of all the gauge generators of a constrained hamiltonian theory. Dirac's conjecture that all secondary first-class constraints generate symmetries is revisited and replaced by a theorem. The algorithm is applied to Yang-Mills theories and metric gravity, a
Recent work reported in the literature suggests that for the long-time integration of Hamiltonian dynamical systems one should use methods that preserve the symplectic (or canonical) structure of the flow. Here we investigate the symplecticness of numerical integrators for constrained dynamics, such