Abstract: It is one of the challenging issues in geosciences to study the physical chemical properties and geochemical behaviors of geological fluids. Compared with conventional approaches of experiments and semi-theoretical modeling, computer simulation based on molecular modeling shows its advantages on quantitative predictions of the physical chemical properties of geological fluids under extreme conditions and emerges as a promising approach to find the characteristics of geological fluids and their interactions in different lithospheres of the Earth interior. In this paper, we give a brief introduction of our experiences in applying computer simulation techniques into the research of geological fluids. The main results can be summarized as follows: (1) we have successfully reproduced the experimental phase behaviors of the typical geological systems with Monte Carlo simulations; (2) through comprehensive isothermal-isobaric molecular dynamics simulations, the PVT data of water have been extended beyond experimental range to about 2000 K and 20 GPa and an improved equation of state for water has been established; (3) based on extensive computer simulations, an optimized molecular potential for carbon dioxide have been proposed, this model is expected to predict different properties of carbon dioxide (volumetric properties, phase equilibria, heat of vaporization, structural and dynamical properties) with improved accuracies; (4) with molecular dynamics simulations and careful analysis, we’ve got various structural, dynamical and thermodynamical properties of lithium chloride ionic solvations and associations, these results not only agree well with experimental data and first principle calculation results, but also reveal some new insights into the microscopic ionic solvation and association processes.

Key words: geological fluids, molecular dynamics, Monte Carlo, computer simulation, physical chemical properties, geochemistry, thermodynamics