BA in Physics
Thomas D. Gutierrez
The cohesive energy, lattice constant and bulk modulus of two simple HCP crystal structures of magnesium and technetium were calculated using the vienna ab initio simulation package (VASP) which is based on density functional theory (DFT). The same properties were determined for TcMg2O4 spinel. The theoretical results of the lattice constant of the pure crystals were compared to experimental results and found to be in excellent agreement with a difference of less than 2%. The results for the lattice constant of the TcMg2O4 spinel were found to be in excellent agreement as well with an error of less than 2%. The bulk modulus and cohesive energy could not be compared to experiment since these properties have not been analyzed for this specific spinel. However, the potential of DFT was recognized through this lack of information and proves to be an attractive method for guiding experimental synthesis. In the grand scheme of things, this was just one variation of the possible spinel’s which can be used to store radioactive Technetium-99 from spent nuclear fuel.