Publications associées à Process function

Tensor network investigation of frustrated Ising models

In spin systems, geometrical frustration describes the impossibility of minimizing simultaneously all the interactions in a Hamiltonian, often giving rise to macroscopic ground-state degeneracies and emergent low-temperature physics. In this thesis, combin ...

EPFL2022

Computational Modeling of the Oxygen Evolution Reaction at Semiconductor-Water Interfaces: A Path Towards Breaking Linear Scaling Relationships

Patrick Gono

Photoelectrochemical water splitting is a promising source of clean, renewable fuel in the form of hydrogen. Despite extensive research endeavors, the widespread adoption of this technology is impeded due to suboptimal catalysts for the oxygen evolution re ...

EPFL2020

Small Electron Polarons in CsPbBr3: Competition between Electron Localization and Delocalization

Alfredo Pasquarello, Stefano Falletta, Julia Anna Wiktor

We study the nature of excess electrons in CsPbBr3 and identify several single and double polaronic states. We emphasize the importance of proper inclusion of the self-interaction corrections for the stability of small electron polarons in this material. W ...

AMER CHEMICAL SOC2020

Hydrogen Diffusion and Trapping in α-Iron: The Role of Quantum and Anharmonic Fluctuations

Michele Ceriotti, Bingqing Cheng

We investigate the thermodynamics and kinetics of a hydrogen interstitial in magnetic α-iron, taking account of the quantum fluctuations of the proton as well as the anharmonicities of lattice vibrations and hydrogen hopping. We show that the diffusivity o ...

2018

Accelerating path integral evaluation of equilibrium and kinetic isotope effects

Konstantin Karandashev

Investigating the effect of isotope substitution on equilibrium and kinetic properties of molecules has become an important tool for estimating the importance of nuclear quantum effects. In this work, we discuss calculating both equilibrium and kinetic iso ...

EPFL2018

How Rhodopsin Tunes the Equilibrium between Protonated and Deprotonated Forms of the Retinal Chromophore

Ursula Röthlisberger, Siri Camee van Keulen, Alicia Solano

Rhodopsin is a photoactive G-protein-coupled receptor (GPCR) that converts dim light into a signal for the brain, leading to eyesight. Full activation of this GPCR is achieved after passing through several steps of the protein's photoactivation pathway. Ke ...

2017

Anharmonic and Quantum Fluctuations in Molecular Crystals: A First-Principles Study of the Stability of Paracetamol

Michele Ceriotti, Piero Gasparotto, Mariana Rossi Carvalho

Molecular crystals often exist in multiple competing polymorphs, showing significantly different physicochemical properties. Computational crystal structure prediction is key to interpret and guide the search for the most stable or useful form, a real chal ...

2016

Who Activates the Nucleophile in Ribozyme Catalysis? An Answer from the Splicing Mechanism of Group II Introns

Ursula Röthlisberger, Giulia Palermo, Lorenzo Casalino

Group II introns are Mg2+-dependent ribozymes that are considered to be the evolutionary ancestors of the eukaryotic spliceosome, thus representing an ideal model system to understand the mechanism of conversion of premature messenger RNA (mRNA) into matur ...

2016

Kinetic isotope effect in malonaldehyde determined from path integral Monte Carlo simulations

Jiri Vanicek, Marcin Rafal Buchowiecki, Jing Huang

The primary H/D kinetic isotope effect on the intramolecular proton transfer in malonaldehyde is determined from quantum instanton path integral Monte Carlo simulations on a fully dimensional and validated potential energy surface for temperatures between ...

Royal Society of Chemistry2014

Direct path integral estimators for isotope fractionation ratios

Michele Ceriotti, Bingqing Cheng

Fractionation of isotopes among distinct molecules or phases is a quantum effect which is often exploited to obtain insights on reaction mechanisms, biochemical, geochemical, and atmospheric phenomena. Accurate evaluation of isotope ratios in atomistic sim ...

American Institute of Physics2014

An inexact proximal path-following algorithm for constrained convex minimization

Volkan Cevher, Quoc Tran Dinh, Anastasios Kyrillidis

Many scientific and engineering applications feature large-scale non-smooth convex minimization problems over convex sets. In this paper, we address an important instance of this broad class where we assume that the non-smooth objective is equipped with a ...

Siam Publications2014

A robust method for inverse transport modelling of atmospheric emissions using blind outlier detection

Martin Vetterli, Benjamin Bejar Haro, Marta Martinez-Camara

Emissions of harmful substances into the atmosphere are a serious environmental concern. In order to understand and predict their effects, it is necessary to estimate the exact quantity and timing of the emissions, from sensor measurements taken at differe ...

2014

Monte Carlo evaluation of the equilibrium isotope effects using the Takahashi-Imada factorization of the Feynman path integral

Jiri Vanicek, Marcin Rafal Buchowiecki

The Feynman path integral approach for computing equilibrium isotope effects and isotope fractionation corrects the approximations made in standard methods, although at significantly increased computational cost. We describe an accelerated path integral ap ...

Elsevier2013

Direct evaluation of the temperature dependence of the rate constant based on the quantum instanton approximation

Jiri Vanicek, Marcin Rafal Buchowiecki

A general method for the direct evaluation of the temperature dependence of the quantum-mechanical reaction rate constant in many-dimensional systems is described. The method is based on the quantum instanton approximation for the rate constant, thermodyna ...

American Institute of Physics2010

Three applications of path integrals: equilibrium and kinetic isotope effects, and the temperature dependence of the rate constant of the [1,5] sigmatropic hydrogen shift in (Z)-1,3-pentadiene

Jiri Vanicek, Tomas Zimmermann

Recent experiments have confirmed the importance of nuclear quantum effects even in large biomolecules at physiological temperature. Here we describe how the path integral formalism can be used to describe rigorously the nuclear quantum effects on equilibr ...

Springer Verlag2010

Path integral evaluation of equilibrium isotope effects

Jiri Vanicek, Tomas Zimmermann

A general and rigorous methodology to compute the quantum equilibrium isotope effect is described. Unlike standard approaches, ours does not assume separability of rotational and vibrational motions and does not make the harmonic approximation for vibratio ...

2009

A method for the enumeration of the floppy modes and the calculation of the associated entropy

Giuseppe Foffi

We present a method that is based on the Ladd-Frenkel (LF) thermodynamic integration for the study of the rigidity of networks of particles bonded together by short-ranged square well attractive potentials. We show that, by taking the limit of the attracti ...

2008

Diabatic free energy curves and coordination fluctuations for the aqueous Ag(+)Ag(2+) redox couple: A biased Born-Oppenheimer molecular dynamics investigation

Ivano Tavernelli

Biased Born-Oppenheimer molecular dynamics simulations are performed to compute redox potential and free energy curves for the redox half reaction Ag(+)-->Ag(2+)+e(-) in aqueous solution. The potential energy surfaces of reactant and product state are line ...

2006