Hello, A change in allocation has been requested: Requester: mchan (Maria Chan) Project: CEES-Si Title: Investigations of silicon surfaces and interfaces for lithium ion batteries Description: We will use total energy DFT calculations to evaluate the adsorption and absorption energy and nudged elastic band migration barriers of Li on and near Si (100), (111) and (110) surfaces with low energy reconstructions. We will also calculate the effects of adsorbed and substitutional impurities on the energetics and kinetics. I will consider 6 types of impurities, 2-3 types of reconstruction per surface orientation, and 10-20 Li position, and combinations thereof. This will amount to 1000-2000 calculations of 100-200 core-hours each. Vibrational frequencies from DFT forces dynamical matrices will be computed in order to aid comparisons with experiments. In addition, energetics and kinetics of Li in nanowires, at the interface between crystalline and amorphous silicon, and between Si and inorganic minerals found to be present at electrode interfaces, will be studied. Interface and nanowire calculations will each consume 500-2000 core-hours and 50-100 calcu lations will be performed. Using the projector-augmented wave method, only valence electrons will be included which reduces computational costs. We will use well-established DFT codes VASP and GPAW, which use a plane wave basis set and real space grids respectively. For large systems such as nanostructures, VASP has been tested on Fusion for computation involving systems with up to 7000 electrons. For routine surface calculations, hard scaling efficiency of 70%-80% has been demonstrated for 64 to 128 cores compared to 8 cores, thus enabling efficient calculations of large numbers of configurations. Please note that I am requesting an allocation for FY2011 significantly higher than that will have been used by the end of FY2010 because my FY2010 allocation did not start until March 2010 and from March to September 2010 I still have access to other machines from previous affiliations that I will no longer have access to in FY2011. Current: undetermined amount Justification: Requested: 300000 A specific reason has been given: The scope of the project has been extended to include: (1) the effects of dopants on lithium insertion into Si and (2) automatic lithiation simulations of bulk, surfaces, amorphous-crystalline interfaces, and nanowires. The automatic lithiation algorithm allows the study of thermodynamic stable phases in the process of lithium insertion into Si, and requires a large number of configurational sampling calculations for each initial Si structure. Please note that the initial allocation of 100,000 SUs for this project was exhausted in December 2011, and early release of another 100,000 SUs was requested which was also exhausted. This work is critical to the Center for Electrical Energy Storage (CEES), a DOE Energy Frontier Research Center, since Si is the forerunning alternative to carbon as anode material for Li-ion batteries and CEES is exerting significant experimental efforts in its investigation. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System