Abstract: A major challenge of our time is to develop new pathways for energy transformation, storage, and use. This 'energy frontier research', aiming at design, synthesis, and manufacture with higher performance and functionality, requires scientific innovative observations far beyond incremental advances in current energy technologies. Traditionally, basic science has relied on two variables or dimensions (namely temperature and composition) of known materials to understand underlying physics. Pressure is regarded as an entirely new dimension of science, which enables us to explore much broader range of thermo-mechanical conditions by accessing extreme states of matter.  

In this presentation, I will show recent progress on our theory-experiment collaborations in this direction. Crystal structure searching using density functional theory enables us to predict novel materials and guides our experiments. I will present our recent successful examples to highlight the importance of integrated experiment-theory collaboration for Energy Frontier Research. I will show our recent discovery of a new silicon allotrope with an orthorhombic structure which is stabilized at ambient conditions. It possesses a quasi-direct band-gap with ~1.3 eV, which is the optimal band-gap for photovoltaic applications. At high pressure, we have discovered a formation of sodium polyhydrides. Interestingly, it exhibits a unique hydrogen substructure, which will be discussed in detail.

Date&Time: July 21, 2014 (Monday), 15:30 - 16:30
Location: 606 Conference Room