Sökning: "Born-Oppenheimer"

Visar resultat 1 - 5 av 19 avhandlingar innehållade ordet Born-Oppenheimer.

1. 1. Four-Body Treatment of the Hydrogen-Antihydrogen System

   Författare :Henrik Stegeby; Piotr Froelich; Alejandro Saenz; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Antimatter; antihydrogen; four-body system; Adiabatic approximation; Born-Oppenheimer; elastic scattering; stabilization method; resonance states; coupled arrangement channels; coupled rearrangement channels; Gaussian Expansion Method; Antimateria; antiväte; fyrkroppars system; adiabatisk approximation; stabilisationsmetoden; resonanstillstånd; spridningstillstånd; kopplade arrangemangskanaler; Quantum Chemistry; Kvantkemi;

   Sammanfattning : This thesis presents a nonadiabatic (4-body) description of the hydrogen-antihydrogen system at a nonrelativistic level. The properties of the system, the rearrangement processes and the possible existence of resonance states are investigated by using a variational method for coupled arrangement channels, the Gaussian Expansion Method, and the stabilization method. LÄS MER

3. 2. Photoelectron Spectroscopy on HCl and DCl : Synchrotron Radiation Based Studies of Dissociation Dynamics

   Författare :Florian Burmeister; Eckart Rühl; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Photoelectron spectroscopy; HCl; DCl; Dissociation dynamics; Born-Oppenheimer approximation; Synchrotron radiation; Fysik; Physics; Fysik; fysik; Physics;

   Sammanfattning : Dissociation dynamics of the ionized molecules HCl and the deuterated system DCl has been studied in gas-phase using synchrotron based photoelectron spectroscopy (PES).The inner-valence "(4σ)-1" photoionization band for DCl and HCl was recorded using maximum resolution in order to probe an interference pattern between a dissociative and a bound electronic state. LÄS MER

4. 3. Fingerprints of light-induced molecular transients : from quantum chemical models of ultrafast x-ray spectroscopy

   Författare :Jesper Norell; Michael Odelius; Sang-Kil Son; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; time-resolved x-ray spectroscopy; quantum chemistry; electronic structure; multi-configurational self-consistent field; density functional theory; molecular dynamics; Born-Oppenheimer dynamics; non-adiabatic dynamics; proton-transfer; charge-transfer; solvatization; Dyson orbital; teoretisk fysik; Theoretical Physics;

   Sammanfattning : Absorption of sunlight generates renewable electricity and powers the growth of plants, but also causes severe damage both to synthetic materials and biological tissue. The wildly varying outcomes of these light-induced processes are ultimately determined by much slighter differences in their underlying reaction pathways, induced by the transient properties of short-lived and miniscule molecules; a powerful approach to their detection and characterization is offered by ultrafast x-ray spectroscopy, with identification of spectral fingerprints and further guidance from quantum chemical models. LÄS MER

5. 4. Error Estimation and Adaptive Methods for Molecular Dynamics

   Författare :Ashraful Kadir; Anders Szepessy; Emanuel Rubensson; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : This  thesis consists of two  papers that  concern error estimates for the Born-Oppenheimer molecular dynamics, and adaptive algorithms for the Car-Parrinello and Ehrenfest molecular dynamics. In Paper I, we study error estimates for Born-Oppenheimer molecular dynamics with  nearly crossing potential  surfaces. LÄS MER

7. 5. Numerical Methods for Molecular Dynamics with Nearly Crossing Potential Surfaces

   Författare :Ashraful Kadir; Anders Szepessy; Emanuel Rubensson; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Numerical Methods; Molecular Dynamics; Nearly Crossing Potential Surfaces; Error Estimation; Adaptive Algorithm; Tillämpad matematik och beräkningsmatematik; Applied and Computational Mathematics;

   Sammanfattning : This thesis consists of four papers that concern error estimates for the Born-Oppenheimer molecular dynamics, and adaptive algorithms for the Car-Parrinello and Ehrenfest molecular dynamics.In Paper I, we study error estimates for the Born-Oppenheimer molecular dynamics with nearly crossing potential surfaces. LÄS MER