National Repository of Grey Literature 3 records found  Search took 0.01 seconds. 
Rezonanční srážky elektronů s molekulami
Formánek, Martin ; Houfek, Karel (advisor) ; Kolorenč, Přemysl (referee)
In the present work we study different approaches for solving the nuclear dy- namics of resonant electron molecule collisions. Namely, we review two methods addressing this phenomenon which are a local complex potential (LCP) approxi- mation and a nonlocal resonance model (NRM). We briefly discuss a numerical implementation of these methods. We show how to derive model parameters for both of them from fixed-nuclei scattering calculations and we implement them in the time independent picture of quantum mechanics. We compare their vibrational excitation cross sections for the diatomic molecule CO. Then we generalize the non- local resonance model for systems with more nuclear degrees of freedom. Output of our work is a computer code producing the vibrational excitation cross sections for systems with two degrees of freedom. We aim to use this code for studying a threshold behavior of the low-energy electron collisions with the CO2 molecule and therefore we review a current state of understanding for this phenomenon. Mea- nwhile we test the functionality of the code by comparing results with those of the LCP approximation on a simple 2D model system.
Study of analytic behavior of scattering quantities in the nonlocal resonance model
Bednařík, Lukáš ; Čížek, Martin (advisor) ; Houfek, Karel (referee)
In the presented thesis we study analytical behavior of vibrational excitation cross sections and probability flux density in nonlocal resonance model. An analytical formula for determining the shape of Wigner cusps from three complex parameters is derived. The results of this formula are compared to numerical calculations with complex scaling method and interpreted within Feynman approach to quantum mechanics. Furthermore, we derive nonlocal continuity equation and show how it implies the multichannel optical theorem. Detail analysis of fluxes in the nonlocal resonance model is used to accelerate the convergence of formula for the dissociative attachment cross section and we present a simple model describing boomerang oscillations. A program in Fortran language is attached to this work. The program allows calculation of vibrational excitation and dissociative attachment cross sections, flux divergences and other quantities specified in this text.
Rezonanční srážky elektronů s molekulami
Formánek, Martin ; Houfek, Karel (advisor) ; Kolorenč, Přemysl (referee)
In the present work we study different approaches for solving the nuclear dy- namics of resonant electron molecule collisions. Namely, we review two methods addressing this phenomenon which are a local complex potential (LCP) approxi- mation and a nonlocal resonance model (NRM). We briefly discuss a numerical implementation of these methods. We show how to derive model parameters for both of them from fixed-nuclei scattering calculations and we implement them in the time independent picture of quantum mechanics. We compare their vibrational excitation cross sections for the diatomic molecule CO. Then we generalize the non- local resonance model for systems with more nuclear degrees of freedom. Output of our work is a computer code producing the vibrational excitation cross sections for systems with two degrees of freedom. We aim to use this code for studying a threshold behavior of the low-energy electron collisions with the CO2 molecule and therefore we review a current state of understanding for this phenomenon. Mea- nwhile we test the functionality of the code by comparing results with those of the LCP approximation on a simple 2D model system.

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