Nicolas Levy | Searcharxiv

arXiv2016

Molecular density functional theory of water including density-polarization coupling

We present a three-dimensional molecular density functional theory (MDFT) of water derived from first-principles that relies on the particle's density and multipolar polarization density and includes the density-polarization coupling. This brings two main benefits: ($i$) a scalar density and a vectorial multipolar polarization density fields are much more tractable and give more physical insight than the full position and orientation densities, and ($ii$) it includes the full density-polarization coupling of water, that is known to be non-vanishing but has never been taken into account. Furthermore, the theory requires only the partial charge distribution of a water molecule and three measurable bulk properties, namely the structure factor and the Fourier components of the longitudinal and transverse dielectric susceptibilities.

physics.chem-ph↗

arXiv2014

Introduction to Classical Density Functional Theory by a Computational Experiment

We propose an in-silico experiment to introduce classical density functional theory (cDFT). Den- sity functional theories, whether quantum or classical, rely on abstract concepts that are non- intuitive. However, they are at the heart of powerful tools and active fields of research in both physics and chemistry. They led to the 1998 Nobel Prize in chemistry. DFT is illustrated here in its most simple and yet physically relevant form: the classical density functional theory of an ideal fluid of classical particles. For illustration purpose, it is applied to the prediction of the molecular structure of liquid neon. The numerical experiment proposed therein is built around the writing of a cDFT code by students in Mathematica. Students thus have to deal with (i) the cDFT theory, (ii) some basic concepts of statistical mechanics of simple fluids, (iii) functional minimization, and (iv) a useful functional programming language. This computational experiment is proposed during a molecular simulation class, but may also be of interest in a quantum chemistry class to illustrate electronic DFT, if one highlights the analogies between the quantum and classical DFTs.

physics.chem-ph↗