Hydrogen Rich Solids Under Pressure Eva Zurek, SUNY at Buffalo, DMR 1005413

1. Hydrogen Rich Solids Under PressureEva Zurek, SUNY at Buffalo, DMR 1005413 • It is widely believed that solid metallic hydrogen will be a high-temperature superconductor. Unfortunately, the pressures necessary to metalize hydrogen are higher than those at the center of the earth. Calculations based upon density functional theory predict that under pressure a number of NaHn (n > 1) crystals are stable. NaH9 is particularly interesting since it is metallic at pressures lower those necessary to metalize hydrogen. This solid may be a superconductor at experimentally achievable pressures. • The expanded metal Li(NH3)4 has the lowest melting point of any metal known. At 89K it forms a bronze, stable, crystalline solid with fascinating magnetic and electrical properties. Calculations have been carried out to study this solid at ambient conditions, and under pressure. 1. Supercell of the pressure-stabilized sodium polyhydride, NaH9, and its density of states at 300 GPa 2. The highest occupied molecular orbital of the Li(NH3)4 molecule, the building block of the solid

2. Open Source Software for Structure PredictionEva Zurek, SUNY at Buffalo, DMR 1005413 We have written and released XtalOpt, which is an evolutionary algorithm that incorporates the results of quantum mechanical calculations, as well as those using interatomic potentials, in order to determine the most stable geometries or crystal structures of solids. XtalOpt has been written as an extension to the molecular editor Avogadro, and released under the open-source GNU Public license. XtalOpt has been interfaced with various codes used to study solids, and has an easy to use, intuitive graphical interface. It is available free of charge or registration at from the open-molecules website. Screen shots from XtalOpt http://xtalopt.openmolecules.net/