Hello, A change in allocation has been requested: Requester: handany (Handan Yildirim) Project: md_pls_dft_for_TiO2 Title: First Principles and Classical Molecular Dynamics Calculations of Lithium Intercalation into TiO2 Surfaces and Nanostructures Description: In our preliminary simulations, we have obtained insights regarding the diffusivity of Li in the TiO2 polymorphs including amorphous. The effects of concentration, mechanism for diffusion, and host morphology on the diffusivity of Li ions are explored by comparing the results obtained for anatase, rutile and amorphous TiO2. The structural changes upon certain concentration of Li intercalation into these systems are studied extensively. The structural properties and the diffusivity of Li ions in the new crystal phase are explored in details. The results of MD simulations at relatively low temperatures are analyzed to identify Li diffusion mechanisms in these systems, and the obtained mechanism is used to calculate the corresponding isolated Li diffusion energetics using DFT. Our MD results, in summary, showed that Li ions diffuse with different mechanism at each system that is mostly determined by the host lattice structure. For instance, in anatase, the diffusi on is 3D in nature, while for rutile, the diffusion proceeds in 1D through the open channels provided by the intrinsic characteristic of the host lattice. Our DFT calculations also confirmed this observation. For the systems under study, for sufficient convergence of the total energy of about 100-150 atoms system with the chosen parameters required 100 plus ionic iterations. For our simulations, we have mostly used 32 CPU’s per job, and at least 5 jobs, on average, run simultaneously; we expect bit more higher distribution of jobs for the extension of our study, as we need to explore several sizes for tubes and nanoparticles. Note that we will also explore Li adsorption and sub-surface diffusion on these nanoparticles and nanotubes thus it is inevitable that we require significant computational resources to complete this part of the proposed study. We performed classical MD simulations to study Li diffusion energetics and dynamics under several conditions using the DL-POLY code. We have gained significant insights into the role of concentration and morphology on the diffusivity of Li ions in the bulk TiO2 polymorphs. Additionally, phase transition with high Li load and under certain pressure range is observed with these studied for nanosecond time scales. These simulations are indeed computationally intensive as the systems have large number of atoms. Our calculations for this part of the study are performed with a very fine time step (~0.2 fs in general), requiring long simulation hours even for 5ns (due to the type of the potential used). For the calculations of nearly 5000 to 10000 atoms for simulating 5ns, 25 to 50 millions simulation steps are needed. As our simulations extend to several temperature and concentration ranges, the need for intensive computational time can be understood. Our proposed simulations will require more computational resources as we plan to study size effects, and the effect of thickness, outer radius and length of the nanotubes on the diffusivity of Li ions and the structural changes upon lithiation. We will explore phase transitions for both nanoparticles and nanotubes for wide ranges of pressure values. The effect of the size of the nanoparticles will be evaluated to determine the role of nanostructuring on the transition pressure. The sizes will range between 2nm to 20nm and the simulations will be performed at least 1ns timescale for each size. These simulations will clearly require significant computational resources. We anticipate that we will be running of about 10 to 20 jobs per day to complete this part of the proposed research. Current: undetermined amount Justification: In roughly three months, we required over 250,000 CPU hours for the combination of MD and DFT calculations including testing of classical potential used, and the convergence tests for DFT studies. These calculations have been performed on the CNM’s carbon cluster, but this resource is fully subscribed and is being increasingly used for external user projects. Thus, we require computational resources on Fusion to complete our proposed project. For a full year, we estimate that approximately 500,000 CPU hours will be sufficient. Requested: 250000 A specific reason has been given: Further calculations are needed to test the size effects on the diffusion for the nanostructures studied. In order to complete this study, we require the additional time 0f 250,000 core-hours. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System