Publications related to Helium atom

Modelling of metal alloys in realistic conditions with machine learning

Computer simulations based on statistical methods have emerged as a powerful tool for studying structure-property relationships at the atomistic level. However, to provide reliable insights into materials in realistic conditions, it is essential to accurat ...

EPFL2023

Ultrafast Resonant Interatomic Coulombic Decay Induced by Quantum Fluid Dynamics

Marcel Drabbels, Andrew Daniel Bonnar Clark, Verónica Oliver Álvarez de Lara, Daniela Rupp

Interatomic processes play a crucial role in weakly bound complexes exposed to ionizing radiation; therefore, gaining a thorough understanding of their efficiency is of fundamental importance. Here, we directly measure the timescale of interatomic Coulombi ...

American Physical Society2021

Efficient implementation of atom-density representations

Michele Ceriotti, Guillaume André Jean Fraux, Till Junge, Félix Benedito Clément Musil, Michael John Willatt, Max David Veit, Alexander Jan Goscinski

Physically motivated and mathematically robust atom-centered representations of molecular structures are key to the success of modern atomistic machine learning. They lie at the foundation of a wide range of methods to predict the properties of both materi ...

2021

Magnetic exchange interactions in monolayer CrI3 from many-body wavefunction calculations

Oleg Yazyev, Ravi Yadav, Michele Pizzochero

The marked interplay between the crystalline, electronic, and magnetic structure of atomically thin magnets has been regarded as the key feature for designing next-generation magneto-optoelectronic devices. In this respect, a detailed understanding of the ...

IOP PUBLISHING LTD2020

Atomistic-continuum coupling of random alloys

William Curtin, Till Junge, Shankha Nag

Random alloys are multicomponent systems where the atomic type on each lattice site is independent of the atom types on any other lattice site. The fluctuations in local atomic configurations inherent to the random alloy prevents the accurate application o ...

IOP PUBLISHING LTD2019

Atom-density representations for machine learning

Michele Ceriotti, Félix Benedito Clément Musil, Michael John Willatt

This has led to a proliferation of alternative ways to convert an atomic structure into an input for a machine-learning model. We introduce an abstract definition of chemical environments that is based on a smoothed atomic density, using a bra-ket notation ...

2019

Properties of helium bubbles in covalent systems at the nanoscale: A combined numerical and experimental study

Cécile Hébert, Duncan Thomas Lindsay Alexander

The properties of nanometric-sized helium bubbles in silicon have been investigated using both spatially resolved electron-energy-loss spectroscopy combined with a recently developed method, and molecular-dynamics simulations. The experiments allowed for a ...

Amer Physical Soc2017

Average-atom interatomic potential for random alloys

William Curtin, Céline Varvenne

An average-atom (A-atom) embedded-atom-method potential for random multicomponent alloys at any composition is derived analytically and validated by comparing A-atom and true random alloys bulk and defect properties, in model Fe-Ni-Cr systems. The A-atom c ...

Amer Physical Soc2016

Thermodynamic properties of average-atom interatomic potentials for alloys

William Curtin, Wolfram Georg Nöhring

The atomistic mechanisms of deformation in multicomponent random alloys are challenging to model because of their extensive structural and compositional disorder. For embedded-atom-method interatomic potentials, a formal averaging procedure can generate an ...

Institute of Physics2016

Extracting partial decay rates of helium from complex rotation: autoionizing resonances of the one-dimensional configurations

Pierre Lugan

Partial autoionization rates of doubly excited one-dimensional helium in the collinear Zee and eZe configuration are obtained by means of the complex rotation method. The approach presented here relies on a projection of back-rotated resonance wave functio ...

IOP Publishing2015

Visualization of electronic density

The spatial volume occupied by an atom depends on its electronic density. Although this density can only be evaluated exactly for hydrogen-like atoms, there are many excellent algorithms and packages to calculate it numerically for other materials. Three-d ...

Elsevier Science Bv2015

Heavy vector triplets: bridging theory and data

Andrea Wulzer, Duccio Pappadopulo, Riccardo Torre, Andrea Thamm

We introduce a model-independent strategy to study narrow resonances which we apply to a heavy vector triplet of the Standard Model (SM) group for illustration. The method is based on a simplified phenomenological Lagrangian which reproduces a large class ...

Springer Nature2014

Dynamics of Excited Sodium Atoms Attached to Helium Nanodroplets

Marcel Drabbels, Evgeniy Loginov

The dynamics of laser-excited sodium atoms at the surface of helium nanodroplets has been investigated as a function of quantum state. For all cases excitation of the system leads to desorption of the sodium atom from the droplet surface. The mean kinetic ...

American Chemical Society2014

Molecular Dynamics Simulations of Helium Atoms Clustering in bcc Iron

Ning Gao

Helium atoms are known to have a significant impact on materials used in fission and fusion reactors. In particular, the presence of helium atoms can change the mechanical properties and degrade the lifetime of reactors. In order to develop the helium-resi ...

EPFL2011

State-selective spectroscopy of water up to its first dissociation limit

Thomas Rizzo, Oleg Boyarkine, Pavlo Maksyutenko, Maxim Grechko

A joint experimental and first-principles quantum chemical study of the vibration-rotation states of the water molecule up to its first dissociation limit is presented. Triple-resonance, quantum state selective spectroscopy is used to probe the entire ladd ...

2009

Photoexcitation and photoionization dynamics of doped liquid helium-4 nanodroplets

Evgeniy Loginov

The photoexcitation and photoionization dynamics of sodium atoms deposited on the surface of helium nanodroplets and aromatic molecules (aniline, phenol and toluene) embedded in the interior of droplets have been investigated by a variety of spectroscopic ...

EPFL2008

First-principles investigation of symmetric and antisymmetric exchange interactions of SrCu2(BO3)(2)

Frédéric Mila

We report on a first-principles investigation of the electronic structure and of the magnetic properties of the quasi-two-dimensional Mott insulator SrCu2(BO3)(2). Based on the hopping integrals and Coulomb interactions calculated with local-density approx ...

2008

Synergistic effects of PKA and helium on primary damage formation in Fe-0.1%He

Robin Schäublin, Zhongwen Yao, Gang Yu

Molecular dynamics (MD) simulation of displacement cascades in Fe-0.1%He are used to investigate the synergistic effects of primary knock-on atoms (PKA) and He on the irradiation damage production at temperatures between 10 K and 523 K. The results indicat ...

2007

Photodissociation of Alkyl Iodides in Helium Nanodroplets II: Solvation Dynamics

Marcel Drabbels, Andreas Braun

The solvation dynamics of non-thermal species in liquid helium has been investigated by photolyzing alkyl iodide molecules, CH3I, C2H5I and CF3I, embedded in helium nanodroplets. The iodine and CH3 fragments are found to leave the droplets solvated by a fi ...

2007

Study of cascades damage in Ni by MD with different interatomic potentials

Robin Schäublin, Zhongwen Yao

Molecular dynamics (MD) simulations, performed with embedded atom potentials, are used to understand the formation of defects following displacement cascades in Ni. Different empirical potentials, presenting large differences in stacking fault energy (SFE) ...

2007