Mer. 18/11/2015 14:00 ****Bibliothèque LUPM, Bat. 13, 4ieme etage****Séminaire
POIRIER Bill (Texas Tech University)
****Jour et lieu inhabituels****
Quantum Mechanics Without Wavefunctions
Quantum mechanics is the theory that describes the behavior of matter at the nano scale.
Though routinely applied to the electrons in a molecular system, quantum theory is generally not applied to the atomic nuclei (except for very simple molecules), because such “exact quantum dynamics” (EQD) calculations are regarded to be too difficult. This is due to the “curse of dimensionality”: the computational (CPU) cost scales exponentially with system dimensionality. Nevertheless, quantum dynamical effects are known to be important in a wide range of molecular applications, and must therefore be accounted for at least approximately, if sensible numerical simulations are to be performed.
In this presentation, we will discuss powerful new EQD methods developed in recent years, as well as applications. The methods are mostly based on so-called “quantum trajectories”—similar to those used in Bohmian mechanics, but arising from a completely new formulation of quantum mechanics for which the wavefunction Ψ(t, x) plays no role. Instead, quantum states are represented solely as ensembles of real-valued probabilistic trajectories, x(t, C), where C is a trajectory label. The applications discussed span a broad range, from models to highly accurate treatments of real molecules, and will be drawn from the following: (1) wavepacket barrier scattering; (2) extremely deep tunneling; (3) coupled 2D model chemical reaction system; (4) collinear H+H2 reaction; (5) hydrogen adsorbate dynamics on carbon nanotubes; (6) Fluxional H atom scrambling dynamics in Fe(H)2(H2)(PEtPh2)3 coordination complex.
---------Pour plus d'informations, merci de contacter Moultaka G.