Hello, A change in allocation has been requested: Requester: jlow (John J. Low) Project: metadissolve Title: Ab Initio Molecular Dynamics Simulations of Aqueous Reactions of AluminoSilicates Description: The project will predict the rates of aqueous polymerization reactions of aluminosilicates with ab initio molecular dynamics. We will generate free energy surfaces for dimerization reactions of SiOH4 + SiOH4, Al(OH)3 + SiOH4 and B(OH3) + SiOH4 in water and vacuum. Each of these reactions will carried in pH neutral, acidic (1M HCl) and basic (1M NaOH) solutions to model the effect of pH on these reactions. We will use metadynamics to define the reaction coordinate and estimates of free energies. Umbrella sampling will be use to predict accurate free energies and estimates of rates. CPMD (http://www.cpmd.org), PLUMED (http://www.plumed-code.org) and WHAM (http://membrane.urmc.rochester.edu/content/wham) will be used in this project. CPMD is a plane-wave pseudopotential code which exploits Carr-Parrinello Molecular Dynamics. CPMD is very efficient method for ab initio molecular dynamics. PLUMED is an open source plugin, which works together with CPMD, for free energy calculations in molecular systems. Although CPMD can do metadynamics, PLUMED implements the reaction path collective variable (RPCV). The RPCV should increase the efficiency of metadynamics and umbrella sampling. WHAM is a program which performs a weighted histogram analysis of the trajectory from umbrella sampling to generate the free energy changes along the reaction coordinate. CPMD is a highly scalable parallel code. The hybrid MPI/openMP Version of CPMD 3.15.3 scales very well. CPMD can use 560 cores on either blues or fusion very efficiently for these models considered in this project. Additional scaling can be obtained with multiple walkers and task groups, which is available in CPMD. This will enable additional levels of parallelism could scale efficiently to thousands of cores. PLUMED implements a reaction path collective variable will allow us to simulate this reaction with one dimensional metadynamics. One dimensional metadynamics is at least two to three times more efficient than two or three dimensional sampling. PLUMED will increase the efficiency of our metadynamics and umbrella sampling by a factor of two to three. Current: undetermined amount Justification: Requested: 200000 A specific reason has been given: More time is needed to complete calculations for publication. More experiments were required to define the correct collective variables for the desired reactions than planned. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System