Options for Research and Educational Computing
East Carolina University's SGI Origin 350 (Zeus) continues the renaissance in high-performance computing (HPC) with hardware and software solutions specifically optimized for complex technical research computing tasks. The independent, modular scalability of CPUs, I/O bandwidth, system bandwidth, memory, storage, and graphics combine together to make the SGI Origin 350 an ideal choice for solving larger and more complex problems than can be solved with traditional desktop computing solutions. Promoting easy integration with educational visualization and data management further maximize a return-on-investment.
The paddlewheel molecule W2(hpp)4 has the lowest ionization potential known for any stable neutral molecule. Here the bridging ligand, hpp, is the anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-1]pyrimidine. This exceptionally low ionization potential makes these molecules extremely good Lewis bases. We employ the Fukui function, calculated with density functional theory, to elucidate that the direction of attack by electrophilic reagents. Besides the obvious importance of this complex, we are motivated by the fact that, on the basis of molecular orbital diagram previously presented for this molecule, frontier molecular orbital theory (incorrectly) predicts that electrophiles would attact the metal-metal bond. The Fukui function, mapped upon an isosurface of the elctron density corresponding to the Van der Waals surface, correctly predicts the end on attack, depicted by the red area in the image below.
All calculations performed on the ECU SGI Origin 350 with the DMol3 software package. L.J. Bartolotti and P.W. Ayers, J. Phys. Chem. 109 (2005) 1146-1151