The Sound of a Different Bell: Density Functional Theory as a Tool for the Study of Classical Liquids

摘要

Density-functional methods have become the cornerstone of state-of-the-art ab-initio calculations of materials properties, and recently a vast interest has arisen about the possibility of exploiting the full power of the Hohenberg-Kohn theorem by avoiding the use of wavefunctions altogether. A similar approach (with the energy replaced by the Helmholtz free-energy) can be used to study complex classical fluids at finite temperature and in particular highly-asymmetric, charged fluids. In these systems, in fact, we are faced with a similar problem to the one we face while trying to compute the properties of a system composed by ions and electrons; namely, we have two species of particles, the 'big' ones — macromolecules (macroions) instead of ions — and the 'small' ones — ions (microions) instead of electrons. Again, in analogy with the quantum case, our aim is to exploit the fact that the small particles move typically much faster than the big ones by assuming that the former follow adiabatically the latter. Thus, we may expect that the techniques needed for the solution of the classical problem can be of help for the solution of the quantum problem and vice versa.