ABSTRACT
Potential Truncations ........................................................................ 137 6.3 Methods ........................................................................................................ 138
6.3.1 Direct Correlation Function Matching ............................................. 138 6.3.2 Truncation ......................................................................................... 139 6.3.3 Distance Shifting .............................................................................. 140 6.3.4 Long-Range Modeling ...................................................................... 141 6.3.5 Transforms ........................................................................................ 147 6.3.6 Finite-Size Scaling ........................................................................... 147 6.3.7 Adaptive Resolution .......................................................................... 148
6.4 Direct Correlation Function Matching-Mixtures of Polyatomic Molecules ...................................................................................................... 148 6.4.1 Method .............................................................................................. 148 6.4.2 Results ............................................................................................... 152 6.4.3 Model Fluids ..................................................................................... 153 6.4.4 LJ Fluids ........................................................................................... 153 6.4.5 LJ/ Stockmayer Mixtures ................................................................... 153 6.4.6 Comparison with Existing Approaches ............................................ 155 6.4.7 Aqueous Alcohol Mixtures ............................................................... 156
6.5 Future Applications ...................................................................................... 159 6.5.1 Enzyme Solutions ............................................................................. 160 6.5.2 Diffusion and Reaction ..................................................................... 161
6.6 Conclusions ................................................................................................... 161
Abstract: The thermodynamic properties obtained in the Fluctuation Solution Theory (FST) are based on spatial integrals of molecular total correlation functions (TCFs) between component pairs in the mixture. Molecular simulation, via either molecular dynamics (MD) or Monte Carlo (MC) calculations, can yield these correlation functions for model inter-and intramolecular potential functions. However, system-size limitations and statistical noise cause uncertainties in the functions at long range, and thus uncertainties or errors in the integrals. A number of methods such as truncation, distance shifting, longrange modeling, transforms, direct correlation function (DCF) matching, nitesize scaling, and adaptive resolution, have been explored to overcome these problems. This chapter reviews the issues and published work associated with using molecular simulation to obtain FST properties. The results suggest that molecular simulation should now be more fully utilized for obtaining quantitative FST thermodynamic properties of solutions.
