Hello, A new project on the LCRC cluster has been requested. Please forward the information on to the LCRC Allocation sub-committee. Applicant's name: John J. Low Applicant's institution: ANL Applicant's division: CLS Project Name: metadisolve Project title: Ab Initio Molecular Dynamics Simulations of Aqueous Reactions of AluminoSilicates Associated funding: Other Systems: Science: The reactions of Aluminosilicates in water are important in nuclear waste storage, zeolite synthesis, hydrothermal stability and mineralogy. These reactions involve changes in the coordination of reactants and products which can be difficult to model with continuum models of solvents often exploited in ab initio simulations of these reactions. We propose to model the kinetics of the polymerization reactions of aluminosilicates in solution and on surface of amorphous aluminosilicates. This study will establish the utility of advanced molecular dynamics with a explicit solvent models over implicit solvent models. Project 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. We expect that there will three members of this project. Project URL: Requested allocation: 900000 Q1: 225000 Q2: 225000 Q3: 225000 Q4: 225000 Justification: CPMD is well known as a program with efficient parallel scaling. I have documented the scaling of CPMD in previous project reports for aimd_catalysis. The table below show the scaling of CPMD for Cellobiose (C12O11H22) dissolved in 1M HCL (6HCl + 256 H2O) for a total on 569 atoms. CPMD scaling on blues on cellobiose in 1M HCl. MPI OMP Task # of elasped time Core cores (seconds) 216 1 1 216 31138 216 4 1 864 9180 432 4 4 1728 5695 432 8 4 3456 4290 The new version of CPMD (3.17.1) is claimed to scale better then 3.15.3. Using the new version will likely increase the efficiency of the code. It is possible that performance profiling of the code will reveal opportunities for vectorization. We study the CPU and communications bottlenecks of the code to determine whether code modifications may improve performance. The requester has used undetermined amount hours of their initial startup project. In addition to approving an initial amount, please specify a Category and Subcategory for this project. For a list of the current selection of approved categories, please see: https://wiki.lcrc.anl.gov/wiki/Processes/Categories Once the Allocation committee has approved the project, please go to the Project Management page to create it: https://accounts.lcrc.anl.gov/projects.php Thank You, The LCRC Accounts System