Publications associées à Approximation BKW

Large-cage occupation and quantum dynamics of hydrogen molecules in sII clathrate hydrates

Richard Gaal, Livia Eleonora Bove Kado, Umbertoluca Ranieri

Hydrogen clathrate hydrates are ice-like crystalline substances in which hydrogen molecules are trapped inside polyhedral cages formed by the water molecules. Small cages can host only a single H-2 molecule, while each large cage can be occupied by up to f ...

Aip Publishing2024

Low-Rank Tensor Methods for High-Dimensional Problems

Christoph Max Strössner

In this thesis, we propose and analyze novel numerical algorithms for solving three different high-dimensional problems involving tensors. The commonality of these problems is that the tensors can potentially be well approximated in low-rank formats. Ident ...

EPFL2023

Effect of a temperature gradient on the screening properties of ionic fluids

Andrea Grisafi, Federico Grasselli

The electrostatic screening properties of ionic fluids are of paramount importance in countless physical processes. Yet the screening behavior of ionic conductors out of thermal equilibrium has to date mainly been studied in the context of thermoelectric p ...

AMER PHYSICAL SOC2023

Identifying Large Charge operators

Riccardo Rattazzi, Alexander Monin, Gil Badel

The Large Charge sector of Conformal Field Theory (CFT) can generically be described through a semiclassical expansion around a superfluid background. In this work, focussing on U(1) invariant Wilson-Fisher fixed points, we study the spectrum of spinning l ...

Springer Nature2023

Influence of static correlation on the magnon dynamics of an itinerant ferromagnet with competing exchange interactions: First-principles study of MnBi

Henrik Moodysson Rønnow, Thorbjørn Skovhus

We present first-principles calculations of the dynamic susceptibility in strained and doped ferromagnetic MnBi using time-dependent density functional theory. In spite of being a metal, MnBi exhibits signatures of strong correlation and a proper descripti ...

AMER PHYSICAL SOC2022

Normalized Gaussian path integrals

Giulio Corazza

Path integrals play a crucial role in describing the dynamics of physical systems subject to classical or quantum noise. In fact, when correctly normalized, they express the probability of transition between two states of the system. In this work, we show ...

AMER PHYSICAL SOC2020

Semiclassical analysis of the quantum instanton approximation

Jiri Vanicek, Christophe Louis Joseph Jean-Luc Vaillant

We explore the relation between the quantum and semiclassical instanton approximations for the reaction rate constant. From the quantum instanton expression, we analyze the contributions to the rate constant in terms of minimum-action paths and find that t ...

2019

Geometric Integrators for Nonadiabatic Molecular Quantum Dynamics Induced by the Interaction with the Electromagnetic Field

Aurélien Kevin Fabrice Patoz

Understanding the elementary steps involved in a chemical reaction forms the cornerstone of physical chemistry research. One way to deepen this understanding is by studying chemical and physical processes using linear and nonlinear spectroscopic techniques ...

EPFL2017

Quantifying Electronic Phenomena in Organic Chromophores

Antonio Prlj

Challenging ground and excited state problems in the chemistry of common organic chromophores are investigated with state-of-the-art quantum chemical methods. We present a comprehensive excited state molecular dynamics analysis of (a) fundamental building ...

EPFL2017

Dynamical Low Rank approximation of PDEs with random parameters

Eleonora Musharbash

In this work, we focus on the Dynamical Low Rank (DLR) approximation of PDEs equations with random parameters. This can be interpreted as a reduced basis method, where the approximate solution is expanded in separable form over a set of few deterministic b ...

EPFL2017

Efficient Inversion of Multiple-Scattering Model for Optical Diffraction Tomography

Michaël Unser, Thanh-An Michel Pham, Emmanuel Emilien Louis Soubies

Optical diffraction tomography relies on solving an inverse scattering problem governed by the wave equation. Classical reconstruction algorithms are based on linear approximations of the forward model (Born or Rytov), which limits their applicability to t ...

2017

Error Analysis of the Dynamically Orthogonal Approximation of Time Dependent Random PDEs

Fabio Nobile, Eleonora Musharbash

In this work we discuss the dynamically orthogonal (DO) approximation of time dependent partial differential equations with random data. The approximate solution is expanded at each time instant on a time dependent orthonormal basis in the physical domain ...

2015

Accelerating quantum instanton calculations of the kinetic isotope effects

Jiri Vanicek, Konstantin Karandashev

Path integral implementation of the quantum instanton approximation currently belongs among the most accurate methods for computing quantum rate constants and kinetic isotope effects, but its use has been limited due to the rather high computational cost. ...

American Institute of Physics2015

Qualitatively Incorrect Features in the TDDFT Spectrum of Thiophene-Based Compounds

Anne-Clémence Corminboeuf, Basile Curchod, Alberto Fabrizio, Antonio Prlj, Leonard Floryan

Ab initio molecular electronic structure computations of thiophene-based compounds constitute an active field of research prompted by the growing interest in low-cost materials for organic electronic devices. In particular, the modeling of electronically e ...

2015

Gas phase infrared spectra from quasi-classical Kubo time correlation functions

Sara Bonella

We generalise the recently developed phase integration method (PIM) to obtain a computable approximation of the Kubo expression for quantum time correlation functions. Our scheme combines exact sampling of the quantum thermal density with classical dynamic ...

Taylor & Francis2015

Tunneling conductivity in anisotropic nanofiber composites: a percolation-based model

Claudio Grimaldi

The critical path approximation ('CPA') is integrated with a lattice-based approach to percolation to provide a model for conductivity in nanofiber-based composites. Our treatment incorporates a recent estimate for the anisotropy in tunneling-based conduct ...

Institute of Physics2015

Coherent creation and destruction of orbital wavepackets in Si:P with electrical and optical read-out

The ability to control dynamics of quantum states by optical interference, and subsequent electrical read-out, is crucial for solid state quantum technologies. Ramsey interference has been successfully observed for spins in silicon and nitrogen vacancy cen ...

Nature Publishing Group2015

Initial or final values for semiclassical evolutions in the Weyl–Wigner representation

David Eduardo Zambrano Ramirez

Initial value representations are constructed to avoid the search for trajectories that are only defined in semiclassical approximations by their boundary conditions. We show how to incorporate these procedures within the full Weyl representation, so that ...

2013

A Classical and Quantum Trajectory Description of Nonadiabatic Dynamics within Time-Dependent Density Functional Theory

Basile Curchod

Characterizing and predicting the nuclear dynamics of electronically excited molecules is of paramount importance to the understanding of photochemical and photophysical processes in molecules and to the development of new technologies in domains like sola ...

EPFL2013

Efficient DFT+U calculations of ballistic electron transport: Application to Au monatomic chains with a CO impurity

Gabriele Sclauzero

An efficient method for computing the Landauer-Buttiker conductance of an open quantum system within DFT + U is presented. The Hubbard potential is included in electronic-structure and transport calculations as a simple renormalization of the nonlocal pseu ...

Amer Physical Soc2013