Hello, A change in allocation has been requested: Requester: jrussell (John Russell) Project: lith_ox_md Title: Molecular Dynamics Calculations of Lithium Oxides Description: The goal of this project is calculate structural and thermodynamic properties of lithium-oxide materials and to develop parameters for collaborators studying mesoscale models where experimental values may be unavailable. Our initial approach will be to use a Buckingham potential to model covalent interactions and a Wolf summation potential for elecrostatic interactions in a fixed charge Li2O model as implemented in the LAMMPS molecular dynamics package. Our model systems will include free particles, surfaces and nanocrystalline materials. This modeling approach is well suited for large systems due to the favorable scaling of the potentials and software. LAMMPS is massively parallel with nearly linear scaling with system size which can allow for 100k+ atom models for tens of nanoseconds. We are also developing a variable charge lithium-oxide molecular dynamics potential suitable for modeling lithium superoxide, lithium peroxide, and Li2O. The computational cost of this method is estimated as 25x as expensive as a Buckingham pair potential, but with much greater flexibility to model different lithium-oxide stoichiometries. Current: undetermined amount Justification: LAMMPS is a linear scaling molecular dynamics code. We will be using the Wolf summation potential to model electrostatics, which is very important due to the fact that FFT methods for electrostatics such as PPPM and PME are NlogN scaling. The Wolf summation is directly incoporated into our variable charge model. The variable charge itself has costs due to charge equilibration, which should put it on par with MEAM and AIREBO. In LAMMPS these methods are compared to a Lennard-Jones (LJ) potential as a benchmark reference (LJ = 1.0, Buckingham ~ 1.0). MEAM is rated at 16.5x and AIREBO at 40.6x. This is primarily due to loops over second nearest neighbors. Therefore, we expect the potential to be in the range of 25x scaling. Requested: 125000 A specific reason has been given: We might extend our Li-O molecular dynamics model to include a graphene support. Additional G09 calculations would be performed to develop a model of nucleation of Li2O2 at a defect site on graphene. Specifically we want to see how graphene defect responds to a 1 electron or 2 electron transfer. We will use adsorption of a Li atom to be a model of 1 electron transfer and a Mn atom to be a model of 2 electron transfer. The calculations are quite expensive due to high spin states. 125k would be quite helpful. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System