Kirkwood-Buff Theory For Hard-Core Yukawa Fluids And Its Application

Kirkwood-Buff(KB)theory has been widely utilized in the fields of chemistry and biochemistry,because it is of great importance to the investigation of the local structure and thermodynamic properties of complex fluids.In this dissertation,on the basis of the principle of statistical mechanics,the distribution-function theory and integral equation theory are outlined.Furthermore,the radial distribution function(RDF)and KB integral together with its physical explanation and application to the calculation of phase diagram,compressibility and the derivative of the chemical potential with respect to bulk density are presented.As significant theoretical fundamentals for the study of non-uniform fluid,the density functional theory(DFT),fundamental measure theory(FMT)and mean sphere approximation(MSA)are incorporated to obtain the radial distribution function of hard-core Yukawa(HCY)fluids.Thereafter,the KB integrals are calculated through the computer iterative method at different bulk density,screening parameter and reduced temperature.The present dissertation is divided into four parts,which are listed as follows:Chapter ?: Fundamentals of statistical mechanics for classical fluids.Based on statistical mechanics,the distribution-function theory is introduced and the development of KB theory is given a detailed explanation.The general process for calculating the density profile of the system is presented by means of the DFT for classical fluids.Finally,the physical explanation of KB theory and the physicochemical properties of attractive and repulsive HCY potentials are introduced.Chapter ?: KB theory for the repulsive HCY fluids.By means of the methods of firstorder MSA and FMT together with its modified version,the grand potential for classical DFT is constructed.In addition,the RDF is obtained by minimizing the grand potential.The KB integral is calculated to find the effects of bulk density,reduced temperature and screening parameter.Finally,for the application of KB theory,the compressibility and the derivatives of the chemical potential with respect to bulk density are calculated.Chapter ?: KB theory for the attractive HCY fluids.Based on the same methods discussed in the chapter II,the KB theory for the attractive HCY fluids is investigated.Especially,the influences of bulk density,reduced temperature and screening parameter on KB integral are studied.Moreover,the KB integrals for repulsive and attractive HCY fluids at different screening parameters are also compared.It is found that the phase behavior of attractive HCY fluids is more complex than that of the repulsive HCY fluids.As a result,two phase diagrams of the attractive HCY fluids associated with T*-r* and l-r* are given.Finally,the compressibility and the derivatives of the chemical potential with respect to bulk density are calculated at different screening parameters.Chapter ?: Summary.Some conclusions of the investigation of KB theory for HCY fluids are summarized and the deficiencies for the present study are pointed out.Furthermore,the potential application of KB theory to more complex systems is introduced.It is expected that the application of KB theory could be paid more attention in the fields of physics and chemistry.