Molecular Modeling of Paramagnetic Radiation

Title : Molecular Modeling of Paramagnetic Radiation-induced Defects in Solids

Promoters :
Freddy Callens (EMR) – Ewald Pauwels (CMM) – Henk Vrielinck (DiSC) – Michel Waroquier (CMM)

Type : FWO – research project (4 years)

Duration : 01/01/2008 – 31/12/2011

Summary :
In this project, the properties of paramagnetic radiation-induced defects in solids are theoretically investigated using ab-initio modeling techniques, more specifically based on Density Functional Theory (DFT).  The molecular structure of these defects is investigated with the aid of electron paramagnetic resonance spectroscopy (EPR). A primary goal of this project is to support the structural model assignations by DFT calculation of spin Hamiltonian parameters (g tensors, hyperfine and quadrupole interactions). For paramagnetic defects with spin S=1/2, several program packages offer the possibilities of calculating spin Hamiltonian parameters (for the CP2K package the implementation was performed at the CMM). Within this class of defects, the project focuses on radiation-induced radicals in amino acids, sugars and other model systems for DNA. For defects with S>1/2, the calculations of spin Hamiltonian parameters is far less evident. The projects aims to contribute to this field focusing on ionic solids doped with transition metal or lanthanide ions, with applications as storage phosphors. EPR experiments do not only provide structural information on defects but may also provide details on formation mechanisms, stability and defect level positions in the bandgap. The project aims to confront also this information with theoretical calculations.