Download Adiabatic Perturbation Theory in Quantum Dynamics by Stefan Teufel PDF

By Stefan Teufel

Separation of scales performs a primary position within the realizing of the dynamical behaviour of advanced structures in physics and different typical sciences. A well-known instance is the Born-Oppenheimer approximation in molecular dynamics. This e-book makes a speciality of a contemporary method of adiabatic perturbation idea, which emphasizes the position of potent equations of movement and the separation of the adiabatic restrict from the semiclassical restrict. an in depth creation supplies an outline of the topic and makes the later chapters available additionally to readers much less conversant in the fabric. even if the final mathematical thought in keeping with pseudodifferential calculus is gifted intimately, there's an emphasis on concrete and correct examples from physics. purposes variety from molecular dynamics to the dynamics of electrons in a crystal and from the quantum mechanics of in part restrained platforms to Dirac debris and nonrelativistic QED.

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E. ∆(t) = dist(E(t), σ(H(t)) \ E(t)) . 3) 2 P˙ (s) ∆(s) 2 + ˙ P¨ (s) P˙ (s) H(s) + 2 ∆(s) ∆(s) . 3 is clearly not optimal. However, it nicely displays the two mechanisms responsible for adiabatic decoupling. The size of the error depends on the size of the gap and on the variation of the eigenspaces. If either the gap is too small or the variation of the eigenspaces is too large, then adiabatic decoupling breaks down. On the other hand, if the eigenspaces are constant and only the eigenvalue varies, the subspaces decouple exactly.

In the present setting this separation comes from the fact that the nuclei move slowly compared to the electrons. However, this is only true if the kinetic energies of nuclei and electrons are of the same order of magnitude. But the quadratic dispersion allows the nuclei to become arbitrarily fast and as a consequence, the separation of time scales breaks down and with it adiabatic decoupling. 31) holds only uniformly for bounded kinetic energies of the nuclei as expressed by the L(H 2,ε ⊗ He , H) norm: Bounding ψ0 H 2,ε for the initial wave function ψ0 by a constant independent of ε corresponds to bounding the initial velocities of the nuclei on the macroscopic time-scale by a constant independent of ε, since ε2 p2 ∼ const.

For the following we thus only assume that the gap condition is satisfied locally odinger for some open region Λ ⊂ Rd and we consider solutions of the Schr¨ equation which are initially and stay supported in Λ, at least approximately, for some time. 3 Time-dependent Born-Oppenheimer theory: Part I 51 In order to control the maximal time for which a given initial wave function supported in Λ stays supported in Λ, we apply techniques from semiclassical analysis. To this end we have to approximate the diagonal Hamiltonian by an effective Hamiltonian to which semiclassical analysis can be applied.

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