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: Stephan Hruszkewycz Applicant's institution: ANL Applicant's division: MSD Project Name: bragg_ptychography Project title: Development of algorithmic approaches to simulated and experimental x-ray Bragg ptychography imaging. Associated funding: DOE-Basic Energy Sciences Other Systems: CNM Carbon cluster, ~20k cpu-hrs Science: The push towards nanoscale materials design and functionality creates new and difficult challenges in effectively characterizing structural features in materials at these target length scales. Recently developed coherent x-ray characterization techniques can non-destructively image nanoscale diffracting volumes, thus providing a means of studying the internal structure of nanocrystals. Lensless coherent x-ray diffraction imaging (CXDI) techniques have been developed that generate two-dimensional complex image reconstructions of diffracting planar samples and that yield 3D internal strain fields of isolated nanocrystals from volumetric Bragg diffraction. However, the sample requirements of these CXDI methods make studying three dimensional "as grown" or "as designed" nanomaterials difficult. Nanofocused x-ray Bragg ptychography uses the underlying principles of these CXDI techniques, but overcomes their experimental limitations, making it potentially a very powerful tool for nanoscale characterization in materials. This new technique, which we are developing at the CNM/APS Hard X-ray Nanoprobe, is in its infancy and will benefit greatly from simulations of nanofocused diffraction patterns and image reconstruction strategies in order to optimally design and execute experiments on real materials. Project description: We have developed in-house parallel computing software (C++/MPI) specifically to address issues of experimental design and image reconstruction for ptychographic coherent x-ray imaging. The kinematic x-ray scattering summations at the heart of the simulation scale linearly with the number of processors and incorporate realistic x-ray optic models, simulated materials defects, and real-world detector parameters in order to best recreate experimental conditions at the CNM/APS Hard X-ray Nanoprobe. We plan to explore two outstanding issues in this proposal: 1) to understand the limits of 3D Bragg ptychographic imaging of single dislocations in bulk materials, and 2) to develop strategies for imaging 2D Bragg ptychography imaging first from simulated, then from experimental data of nanoscale twin domains in ferroelectric thin films. Both of these thrusts have never before been explored and, if successful, will lead to high profile publications in the field of coherent x-ray diffraction imaging. The ptychography software package we developed requires standard OpenMPI C++ compiling packages, and is controlled through Bash scripting. No special or proprietary libraries or programs are needed. A typical calculation uses 8-40 cpu's simultaneously using >1Gb of memory to store the atomic structure of the simulated sample in question. The code is efficient in that it is based on an "embarrassingly parallel" algorithm and has been tested and used on the CNM Carbon cluster successfully. The computations proposed here will be performed by the PI, and does not cover any other users. Project URL: Requested allocation: 28000 Q1: 7000 Q2: 7000 Q3: 7000 Q4: 7000 Justification: 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