Research Highlights

Mini-Ckpts: Surviving OS Failures in Persistent Memory
Achievement: Developed a novel warm-reboot capability for the operating system (OS) in extreme-scale high-performance computing (HPC) systems to enable recovery from OS failures with minimal impact on running scientific applications. Significance and Impact: The mini-ckpts framework offers a significantly more efficient solution to recover from operating system failures than traditional checkpoint/restart. It improves the efficiency and productivity of DOE’s extreme-scale HPC systems. Research Details:
Achievement: Developed analysis tools for analyzing system logs from Titan, Jaguar and Eos systems from OLCF to extract characteristics of interest and created fault catalogue.
Overview: Recent advances and success stories in Additive Manufacturing (AM) or 3D printing have resulted in references to the process as the “next industrial revolution.”   Producing parts without defects or that will adhere to failure standards are part of the challenge for the continued rapid growth of the industry.  The variation in parameters during a build can contribute to the formation of defects.
ORNL Materials
Achievement: Designed a polymer for selective and reversible carbon dioxide (CO2) capture. Significance and Impact: The new polymer that is based on amidines can provide a more efficient alternative to conventional polyethyleneimine (PEI) based solid-sorbents for CO2 capture and separation. Research Details: An efficient post-polymer modification to enable  substantially greater CO2 selectivity.
ORNL Materials
Achievement: Devised a novel and accurate computational technique for investigating the self-assembly of large macromolecules, and used this method to reveal the initial stages of self-assembly of the carboxysome, the prototype bacterial micro-compartment.   Significance and Impact: Understanding the self-assembly of bacterial micro-compartments can help designing artificial nano-reactors and membranes.   Research Details:
Achievement: Developed an end-to-end data transfer framework, named LADS, for bulk data transfer for terabit networks that is optimized for parallel file systems on both the source and sink. This work includes techniques to improve data transfer under congestion, without impacting other users of the parallel file systems.  
As rising performance demands confront plateauing resource budgets, approximate computing (AC) has become not merely attractive, but imperative. We have performed a comprehensive survey of techniques for AC in CPU, GPU and FPGA and various processor components (e.g. cache, main memory, secondary storage), along with approximate storage in SRAM, DRAM/eDRAM, and non-volatile memories, e.g. Flash, STT-RAM, etc. We review design of approximate circuits such as adder, multiplier and general logic circuits.
Revealing Various Stacking Patterns Between Layers in Two-dimensional 2D Materials
In this work unique twisted bilayers of MoSe2 with periodic multiple stacking configurations and interlayer couplings were discovered in the narrow range of twist angles, 60± 3°, using ulra-low frequency Raman spectroscopy and first-principle theory. We showed that the slight deviation from 60° creates patches featuring all three high-symmetry stacking configurations (2H or AA′, AB′, and A′B) in one unique bilayer system. In this case, the periodic arrangement of the patches and their size strongly depend on the twist angle.
Extending Supramolecular Polymerization to New Lengths
A molecule, called a nucleoside analog and which is composed of an Adenine moeity and glycol group, was deposited on top of the Au(111) surface and studied with scanning tunneling microscopy and density functional theory calculations. The molecule was found to self-assemble into a supramolecular polymer, i.e., a polymer held by hydrogen bonds, that is not only two order of magnitudes longer than any other polymeric structure made by similar molecules on substrates but also encodes a sequence which is erasable with electron-induced excitation.
Researchers have demonstrated a process to prepare morphologically tailored carbon materials with good electrochemical capacity
Charge density slices in the ab-plane of beryl overlain on the beryl structure. A macroscopic green beryl crystal (emerald) is also shown.
Scientific Achievement Found that, when confined in the ~ 5 Å wide channels in a beryl crystal, the water molecule undergoes quantum tunneling between six symmetrically equivalent positions around the c-axis in the structure. Significance and Impact First evidence of a new quantum tunneling state of the water molecules. 
Misfit heterojunctions formed by van der Waals (vdW) epitaxial growth of one crystalline metal chalcogenide monolayer on anotherwas demonstrated for the first time to form p-n junctions that exhibit a photovoltaic response.  Such heterojunction bilayers that display Moiré periodicity represent a new type of “building block” with unusual optoelectronic properties suitable for energy generation as well as a wide range of other physical phenomena ranging from interfacial magnetism to superconductivity.
Schematic routine for multilevel modeling and refinement of neutron (and X-ray) total scattering data
Scientific Achievement A multilevel modeling and population-based refinement scheme (Figure 1) for neutron total scattering data was developed to capture the true nature of surface termination species present on Ti3C2Tx MXenes (T = surface species, including -OH, -O and -F). The experimentally-derived atomistic models (Figure 2) can replace the currently-used idealized models in predictions of a variety of physical, chemical and applied properties of Ti3C2-based MXenes.
This research was featured on the back cover of the journal on April 7, 2015, (volume 54, issue 15)
A hypercrosslinked polymer was synthesized by a Friedel-Crafts alkylation of a phenolic resin with a robust mesoporous framework to avoid framework shrinkage and maximize retention of organic functional groups.
This research was featured on the back cover of the journal for the September 1, 2015, issue (issue 36)
An effective approach to sulfate separation from aqueous solutions was developed based on crystallization of sulfate-water clusters with a simple ligand self-assembled in situ from water-soluble subcomponents. 
Multimodal analysis of a 500 nm thick phase separated thin-film of  polystyrene/ poly-2-vinylpyridine on a silica substrate
The advancement of a hybrid atomic force microscopy/mass spectrometry imaging platform demonstrating, for the first time, co-registered topographical, band excitation nanomechanical, and mass spectral imaging of a surface using a single instrument is reported.  The mass spectrometry-based chemical imaging component of the system utilized nanothermal analysis probes for pyrolytic surface sampling followed by atmospheric pressure chemical ionization of the gas phase species produced with subsequent mass analysis.
Comparison of the VDOS for water and OH groups extracted from INS measurements at incident energies of 250 and 600 meV (circles) with the VDOS extracted from AIMD simulations of the (110) surface of SnO2 (cassiterite).  BH = wagging mode of bridging hydro
Scientific Achievement Inelastic neutron scattering (INS) studies of water sorbed on tin oxide (SnO2, cassiterite) nanoparticle surfaces at low humidity and ab initio molecular dynamics (AIMD) simulations were independently analyzed to extract the vibrational density of states (VDOS) of water and OH groups, showing the effects of water dissocation and very strong intra-surface H-bonds.
Multidimensional transient absorption microscopy data shows regions with either excitons (red) or free charge carriers (blue), but the majority of the image contains a mixture. Isolating the signatures of these distinct photoexcitations enables quantitati
Spatial localization of distinct photoexcited species were identified in light harvesting perovskite based materials using ultrafast transient absorption microscopy (TAM). 
Helium implantation allows for continuous control of optical band gaps in semiconducting films through the resultant strain — an impossibility
Helium implantation allows for continuous control of optical band gaps in semiconducting films through the resultant strain — an impossibility
Thallium-doping (5%) of BaFe2As2 crystal causes a surprising rise of the antiferromagnetic transition temperature (TN), related to
Compared to pure nickel, tuning chemical composition in binary alloys has altered migration barriers of defects, and significantly affected 
Compositional complexity is found to strongly affect electrical, thermal, and magnetic properties of nickel-containing face-centered
Giant elastic tunabilty—the Young’s modulus changes reversibly over 30% under applied electric fields—was discovered in BiFeO3 epitaxial thin films
Researchers demonstrated that straining the crystal lattice of strontium cobaltite reduces oxygen content even under highly oxidizing conditions,
The detection of local phase transitions remains challenging, and to date most techniques can detect properties that change at macroscopic
Contradicting theoretical expectations, researchers discovered that increased molecular weight of a polymer significantly reduces
Multiferroic materials are important because their electrical and magnetic properties are coupled.  Because BiFeO3 magnetically
Researchers discovered that isolated platinum atoms in copper surfaces efficiently catalyze the selective hydrogenation of 1,3 butadiene, a reaction important for many industrial applications.1 A new generation of catalysts with one Pt atom for approximately every 100 Cu atoms can aid chemical reactions needed for efficiency of fuel cells, catalytic converters and industrial chemicals.
We discovered dislocations in the electrical double layer (EDL) in a room-temperature ionic liquid (RTIL) by direct 3D atomic force microscopy (AFM) imaging with molecular resolution. This unexpected discovery sheds new light on complex dynamics of solid-liquid interfaces and provides insight into their electrochemical behavior.
Scientific Achievement The effects of porous media on precipitation reactions are shown to be important, but poorly understood. Significance and Impact Geochemical reactions within rocks and soils occur in pores.  Yet, there is not agreement on how the pores affect the reactions, which limits the ability ro predict reactions in the subsurface. Research Details
To test a key instrument of a spacecraft that will fly closer to the sun than any before, engineers at Oak Ridge National Laboratory and the University of California–Berkeley used ORNL’s powerful plasma-arc lamp as a solar heat flux simulator. They tested the Fields instrument, which will make direct measurements of electric and magnetic fields, radio emissions and shock waves that course through the Sun’s atmospheric plasma.
While palladium, a common catalyst, oxidizes easily, it has now been shown that palladium films grown on ruthenium are surprisingly inert to
Recent developments in piezoresponse force microscopy (PFM) and spectroscopy revealed the presence of electromechanical
For the first time, researchers have synthesized lateral semiconductor heterojunctions in lithographically patterned arrays within a two-dimensional
Theoretical calculations, based on newly obtained experimental geometries in strained BiFeO3 thin films, predict an almost barrierless
A novel simulation of metallic glasses demonstrates that atomic relaxation modes during deformation depend on the density of local minima in the systems’ underlying potential energy landscape (PEL). The relaxation is mostly localized in a slowly cooled glass, but shows an extra delocalized feature (through a cascade process) in a rapidly quenched glass. This study suggests an avenue to improve ductility of metallic glasses—a long-standing challenge—through the control of the PEL and cooling histories.
A multimodal imaging platform was developed that, for the first time, provides co-registered topographic, nanomechanical, and chemical imaging information (via mass spectrometry) of a surface with submicron pixel size.
Functional Programming Computational Cores Embedded Into Traditional High Performance Computing Language Programs
We demonstrated feasibility of embedding functional programming (FP) computational cores written in Scala into programs written in three traditional languages used to implement high performance computing (HPC) applications: Fortran, C, and C++. Measured the performance and overhead of pilot hybrid FP programs.
Helium ions were used to control the length of a single axis in a crystal lattice, allowing for delicate manipulations of complex behavior. This accomplishment unlocks the door to engineering next-generation complex materials. Crystal lattice structure is of central importance to understanding and controlling complex materials that offer untapped potential functionality, such as high-temperature superconductivity, multiferroicity, and colossal magnetoresistivity. However, current methods of controlling lattice structure are limited.
The electron beam of a scanning transmission electron microscope was applied to generate Se vacancies in a semiconducting monolayer of MoSe2, provide energy to drive the formation and growth of inversion domains and metallic 60¡ grain boundaries, and track the dynamics. These results demonstrate it is possible to construct and characterize functional defects in monolayer materials via controllable electron-beam-guided vacancy engineering.
This atomically resolved study revealed a strong link between oxygen pressure and both surface-structure formation and growth dynamics in manganite thin films. The work provides key insights into controlling atomic-level behavior necessary for growing functional materials, such as manganese oxides  for electronic and solid-oxide fuel cell applications.
The growth and proliferation of lithium dendrites during cell recharge seriously hinder development and application of rechargeable Li-metal batteries. Researchers developed a promising strategy for fabrication of quasi−solid electrolytes with superior lithium ionic conductivities, by using a hollow silica (HS) nanosphere-film architecture that blocks dendrites. 
The US Department of Energy’s Oak Ridge National Laboratory (ORNL) is home to state-of-the-art microscopes at ORNL’s Center for Nanophase Materials Sciences (CNMS). While the center’s microscopes are capable of imaging materials at incredibly small scales—down to individual atoms and even minute deviations in atomic positions determining physics of these materials—these microscopes are also capable of imaging structures extremely quickly.
We live in an imperfect world—and that applies to the materials that make up our fuel cells, magnets, solar cells, batteries, and other energy technologies. Materials contain impurities and defects that influence strength and other properties.