Introduction

Abstract

Historically, classical thermodynamics can be understood as a phenomenological branch of the natural sciences dealing with the influence of heat and work on macroscopic systems. The dawn of quantum mechanics as well as the increase of computational resources led to the evolution and quantification of diverse microscopic perspectives on matter, which treat chemical systems as an ensemble of elementary particles and interactions among them. This thesis focusses on the “atomistic” scale of matter typically employed in chemistry, in which the fundamental units are the atomic nuclei as well as the electrons surrounding them. The availability of efficient software packages for the calculation of molecular properties on the basis of the various first principles methods of quantum chemistry during the last decades as well as the advancement in experimental techniques (for instance in laser spectroscopy) permits the chemical sciences to obtain detailed information in this microscopic time and length scale nowadays

So far as physics is concerned, time’s arrow is a property of entropy alone.

Sir Arthur Stanley Eddington [1]