A5063867924- Microstructure and mechanical properties
- Electron and X-Ray Spectroscopy Techniques
- Machine Learning in Materials Science
- Advanced Electron Microscopy Techniques and Applications
- nanoparticles nucleation surface interactions
- Advanced Chemical Physics Studies
- Metallic Glasses and Amorphous Alloys
- Advanced Materials Characterization Techniques
- Electrocatalysts for Energy Conversion
- Catalytic Processes in Materials Science
- Ion-surface interactions and analysis
- Theoretical and Computational Physics
- Metal and Thin Film Mechanics
- Material Dynamics and Properties
- Spectroscopy and Quantum Chemical Studies
- Molecular Junctions and Nanostructures
- Surface and Thin Film Phenomena
- High-Velocity Impact and Material Behavior
- Fuel Cells and Related Materials
- Force Microscopy Techniques and Applications
- Anodic Oxide Films and Nanostructures
- Glass properties and applications
- Nuclear Physics and Applications
- Fatigue and fracture mechanics
- X-ray Diffraction in Crystallography
Technical University of Denmark
2015-2024
Danish Geotechnical Society
2015-2019
Materials Design (France)
2014
Danish National Research Foundation
2007-2011
Nordic Laboratory for Luminescence Dating
1998
Washington University in St. Louis
1995-1997
The atomic simulation environment (ASE) is a software package written in the Python programming language with aim of setting up, steering, and analyzing atomistic simulations. In ASE, tasks are fully scripted Python. powerful syntax combined NumPy array library make it possible to perform very complex tasks. For example, sequence calculations may be performed use simple 'for-loop' construction. Calculations energy, forces, stresses other quantities through interfaces many external electronic...
Electronic structure calculations have become an indispensable tool in many areas of materials science and quantum chemistry. Even though the Kohn-Sham formulation density-functional theory (DFT) simplifies many-body problem significantly, one is still confronted with several numerical challenges. In this article we present projector augmented-wave (PAW) method as implemented GPAW program package (https://wiki.fysik.dtu.dk/gpaw) using a uniform real-space grid representation electronic...
We used molecular dynamics simulations with system sizes up to 100 million atoms simulate plastic deformation of nanocrystalline copper. By varying the grain size between 5 and 50 nanometers, we show that flow stress thus strength exhibit a maximum at 10 15 nanometers. This is because shift in microscopic mechanism from dislocation-mediated plasticity coarse-grained material boundary sliding region. The allow us observe mechanisms behind grain-size dependence polycrystalline metals.
The high platinum loadings required to compensate for the slow kinetics of oxygen reduction reaction (ORR) impede widespread uptake low-temperature fuel cells in automotive vehicles. We have studied ORR on eight (Pt)-lanthanide and Pt-alkaline earth electrodes, Pt5M, where M is lanthanum, cerium, samarium, gadolinium, terbium, dysprosium, thulium, or calcium. materials are among most active polycrystalline Pt-based catalysts reported, presenting activity enhancement by a factor 3 6 over Pt....
Successful scientific applications of large-scale molecular dynamics often rely on automated methods for identifying the local crystalline structure condensed phases. Many existing structural identification, such as common neighbour analysis, interatomic distances (or thresholds thereof) to classify atomic structure. As a consequence they are sensitive strain and thermal displacements, preprocessing quenching or temporal averaging positions is necessary provide reliable identifications. We...
Nanocrystalline metals, i.e. metals with grain sizes from 5 to 50 nm, display technologically interesting properties, such as dramatically increased hardness, increasing decreasing size. Due the small size, direct atomic-scale simulations of plastic deformation these materials are possible, a polycrystalline system can be modeled computational resources available today. We present molecular dynamics nanocrystalline copper up 13 nm. Two different mechanisms active, one is through motion...
We review the GPAW open-source Python package for electronic structure calculations. is based on projector-augmented wave method and can solve self-consistent density functional theory (DFT) equations using three different wave-function representations, namely real-space grids, plane waves, numerical atomic orbitals. The representations are complementary mutually independent be connected by transformations via grid. This multi-basis feature renders highly versatile unique among similar...
We present a modification of the $\ensuremath{\Delta}$ self-consistent field ($\ensuremath{\Delta}\text{SCF}$) method calculating energies excited states in order to make it applicable resonance calculations molecules adsorbed on metal surfaces, where molecular orbitals are highly hybridized. The $\ensuremath{\Delta}\text{SCF}$ approximation is density-functional closely resembling standard theory (DFT), only difference being that one or more electrons placed higher lying Kohn-Sham instead...
Abstract Recording atomic‐resolution transmission electron microscopy (TEM) images is becoming increasingly routine. A new bottleneck then analyzing this information, which often involves time‐consuming manual structural identification. deep learning‐based algorithm for recognition of the local structure in TEM was developed, stable to microscope parameters and noise. The neural network trained entirely from simulation but capable making reliable predictions on experimental images. method...
The quasicontinuum method is a way of reducing the number degrees freedom in an atomistic simulation by removing majority atoms regions slowly varying strain fields. Due to different ways energy calculated coarse-grained and where all are present, unphysical forces called ``ghost forces'' arise at interfaces. Corrections may be used almost remove ghost forces, but correction nonconservative, ruining conservation dynamic simulations. We show that it possible formulate without these problems...
We study the statistics of plastic rearrangement events in a simulated amorphous solid at $T=0$. Events are characterized by energy release and ``slip volume'', product strain system volume. Their distributions for given size $L$ appear to be exponential, but characteristic event cannot inferred, because mean values these quantities increase as ${L}^{\ensuremath{\alpha}}$ with $\ensuremath{\alpha}\ensuremath{\sim}3/2$. In contrast results obtained 2D models, we do not see simply connected...
Using first-principles calculations we analyze the electronic transport properties of a recently proposed anthraquinone based electrochemical switch. Robust conductance on/off ratios several orders magnitude are observed due to destructive quantum interference present in anthraquinone, but absent hydroquinone molecular bridge. A simple explanation effect is achieved by transforming frontier orbitals into localized thereby obtaining minimal tight-binding model describing relevant energy range...
The structure of liquid water at ambient conditions is studied in ab initio molecular dynamics simulations the NVE ensemble using van der Waals (vdW) density-functional theory, i.e., new exchange–correlation functionals optPBE-vdW and vdW-DF2, where latter has softer nonlocal correlation terms. Inclusion more isotropic vdW interactions counteracts highly directional hydrogen bonds, which are enhanced by standard functionals. This brings about a softening microscopic water, as seen from...
We have simulated plastic deformation of a model Mg-Cu metallic glass in order to study shear banding. In uniaxial tension, we find necking instability occurs rather than can force the latter occur by deforming plane strain, forbidding change length one transverse directions. Furthermore, most simulations notch is used initiate bands, which lie at 45\ifmmode^\circ\else\textdegree\fi{} angle tensile loading direction. The bands are characterized Falk and Langer local measure...
Abstract Nanoparticles have an immense importance in various fields, such as medicine, catalysis, and technological applications. exhibit a significant depression melting point their size goes below ≈10 nm. However, nanoparticles are frequently used high temperature applications catalysis where temperatures often exceed several 100 degrees which makes it interesting to study not only the depression, but also how progresses through particle. Using high‐resolution transmission electron...
We present a model for desorption induced by (multiple) electronic transitions [DIET (DIMET)] based on potential energy surfaces calculated with the delta self-consistent field extension of density-functional theory. calculate CO and NO molecules adsorbed various transition-metal show that classical nuclear dynamics does not suffice propagation in excited state. simple Hamiltonian describing system parameters obtained from excited-state surface this can describe both DIET DIMET regimes...
We develop a combined theoretical and experimental method for estimating the amount of heating that occurs in metallic nanoparticles are being imaged an electron microscope. model thermal transport between nanoparticle supporting material using molecular dynamics equivariant neural network potentials. The potentials trained to Density Functional Theory (DFT) calculations, we show ensemble can be used as estimate errors make predicting energies forces. This both improve networks during...
A Reply to the Comment by J. M. Krans et al.Received 7 September 1994DOI:https://doi.org/10.1103/PhysRevLett.74.2147©1995 American Physical Society