The fifth in a series of successful conferences on the statistical mechanics of liquids sponsored by the Czech Academy of Science - and arguably the most successful to date - was held June 7-12, 1998, in the Czech Republic at Zelezna Ruda in the Sumava National Park. The location, a ski resort near the Czech-German border, provided a picturesque backdrop to a week of excellent talks which formed the program of the Fifth Liblice Conference on the Statistical Mechanics of Liquids.

The Liblice Conference on the Statistical Mechanics of Liquids is a series of unique meeting devoted both to basic research and to the application of molecular-based theories of liquids. The first three conferences were organized by the Chemical Physics Section of the Czechoslovak Chemical Society under the auspices of the Czechoslovak Academy of Sciences in 1983, 1986, and 1990. The fourth conference, held in 1994, was organized jointly by the Academy of Sciences of the Czech Republic and Cornell University. The fifth Conference was again organized jointly by the Academy of Sciences of the Czech Republic and Cornell University, and continued in the spirit of the preceding four meetings to provide an effective forum for contacts and for the exchange of ideas, with emphasis on discussions rather than on formal presentations. The meeting succeeded in a clear picture of the achievements and challenges in both theoretical and applied aspects of the discipline.

The Fifth Liblice Conference on the Statistical Mechanics of Liquids was attended by 112 scientists from around the world and 16 from the host country. A special effort was made by the conference organizers to encourage and facilitate participation by scientists from the former eastern bloc, and at this year’s meeting 10 researchers came from Russia, Ukraine, Slovenia, Poland, and Hungary. The biggest group of foreign participants came from the U.S. (29 participants), followed by the group of 15 Germans and parties of 13 scientists from France and the UK. The U.S. participation was partially supported by travel funds from the U.S. National Science Foundation. The organizers particularly encourage the participation by young scientists. This year, the organizers managed to provide support to more than 20 young participants, in addition to supporting researchers from poor developing countries
### 2. Technical Program

#### 2.1. Interfaces and Fluids in Confined Geometries

#### 2.2. Systems with Association and Complex Fluids

#### 2.3. Ionic Systems and Electrolytes

#### 2.4. Real Fluids and Computer Simulations

#### 2.5. Phase Transitions and Phase Equilibria

#### 2.6. Theory

#### 2.7. Other Features of the Technical Program

### 3. Conclusion

The principle focuses of the meeting were molecular simulation (methodology and applications), theoretical developments, applications to specific systems (such as ionic and polar liquids, associated liquids and aqueous solutions, inhomogeneous fluids, complex systems) and application of molecular-based methods to real liquids. Two mini-symposia, one on fluids in nanoporous materials and the other on ionic systems, were also held as part of the meeting.

The organizing committee for the meeting consisted of Ivo Nezbeda, of the Academy of Sciences of the Czech Republic (chair), Keith E. Gubbins of Cornell University (now affiliated with North Carolina State University) and Nicholas J. Quirke of the University of Wales in Bangor, Wales (now affiliated with Imperial College, London). The organizers were assisted by a international Scientific Advisory Committee.

The opening keynote address was given by Ben Widom from Cornell University on the subject of "Structure and tension of interfaces." This lecture was the 1998 Taylor and Francis Lecture, and is the basis for the paper by Widom published elsewhere in this issue of Molecular Physics. In the remainder of this section, we briefly describe highlights from the other technical sessions.

The growing interest in the behavior of fluids confined to nanoscale geometries and at interfaces we evidenced by the wide range of papers presented on this subject in a series of papers covering a full day of sessions. The sessions began with a keynote address by M. L. Rosinberg, who reviewed experimental studies (e.g., gas adsorption into mesoporous solids such as Vycor glass and fluid-phase separation in disordered porous materials) and theory (such as quench-annealed binary mixture approaches and replica methods). Many of the talks focused on experimental, theoretical and simulation approaches to adsorption into nanoporous materials (Kaneko, Padilla, Nicholson, Sokolowski, Piotrovskaya, Gubbins, Monson and Schoen). Other papers considered simulation and theory of interfaces and adsorption at interfaces (Quirke, Bresme and Winkelmann). A cluster of papers (by Fuchs, MacElroy and Ford) described equilibrium and non-equilibrium approaches to transport properties in confined liquid films of nanoscale thickness.

The session of associating and complex fluids naturally featured studies of water in many of the talks. Cummings and Kalinichev both described molecular simulation approaches to the prediction of structure and hydrogen bonding in supercritical water and aqueous solutions. In particular, the process by which simulation studies were instrumental in leading to improved methods for the interpretation of neutron scattering results on water was a common theme in these two talks. At the other end of the temperature spectrum, Debenedetti described the application of statistical geometry and energy landscape concepts to the low temperature liquid and glassy states of water. Two speakers (Chapman and Jackson) described recent theoretical progress and applications of the statistical associating fluid theory (SAFT) equation of state. Jackson also described simulations and application of SAFT to liquid crystalline systems with polar interaction capable of hydrogen bonding. Hall reported Monte Carlo simulations of lattice models for proteins which permit simultaneous study of both protein folding and protein aggregation behavior.

The sessions on ionic and electrolyte systems began with a review (Barthel) describing both experimental and theoretical approaches to electrolyte solutions. The subsequent talk (Krienke) also served as a review of experimental, theoretical and simulation studies of association in electrolyte solutions. A series of papers (Stell, Kraska, di Caprio, and Chialvo) described various theoretical approaches to electrolyte solutions and ionic association based on integral equations and field theoretic methods. Lynden-Bell presented molecular dynamics calculations, performed in collaboration with Lee and Rasaiah, on ionic mobility in electrolyte solutions at ambient conditions. Blum described a simple, analytically tractable model for water based on a multi-Yukawa closure to the Ornstein-Zernike equation - hence the designation Yukagua! A series of invited talks (by Eisenberg, Nonner and Smith) described modeling, measurement and computer simulation of ion transport in membrane channels, an application area for the ionic-fluid community that is attracting considerable interest. A talk related to this topic, ionic fluids in confined geometries, was given by Chan.

The session on real systems, with focus on computer simulation, began with two talks (by Huber and Johnson) exploring the long-hoped-for goal of being able to develop intermolecular potential models for molecular simulation directly from quantum mechanical calculations. For the noble gases, the situation appears to be satisfactory, but for more complex cases (such as the interaction between perfluoroalkanes and carbon dioxide) quantum chemistry appears to be a long way from predicting intermolecular potentials for simulations at high density. Two papers (del Rio and Padua Agilio) focused on theoretical approaches to the description of real systems. The final five papers (Kofke, Millot, Evans, Lustig and Laird) considered molecular simulation methods. Kofke presented a novel method for modeling Monte Carlo simulation methods for chemical potential calculations that makes it possible to optimize the efficiency of the simulations. Millot described molecular simulations of methanol using a polarizable potential. Evans surprised everyone with an elegant demonstration that one can derive an expression for the temperature of a system that depends only on the positions of the molecules, not on velocities. Evans called this the configurational temperature. Lustig in his very interesting talk presented a new Monte Carlo method for the microcanonical ensemble, while Laird discussed symplectic algorithms. Symplectic algorithms for molecular dynamics simulations have the feature that the dynamical properties which are known to be conserved (e.g., the total energy in the microcanonical ensemble) are explicitly constants of the motion generated by the algorithm.

The session on phase transitions and phase equilibria began with a review by Panagiotopoulos of recent progress in molecular simulation methods for predicting phase equilibria - in particular, the advantages of the histogram reweighting method were described. The application of the Gibbs ensemble Monte Carlo method to phase equilibria in bead-spring (in which the beads are hard spheres) was described by de Pablo and to multiphase systems by Lopes. Just as the Gibbs ensemble Monte Carlo method for phase equilibria can be viewed as the simulation of two systems at the same temperature and pressure constrained by equality of chemical potential, a Gibbs-ensemble-like approach to reactions would be implemented by imposing constraints on linear combinations of the chemical potentials of reactants and products. This is the essence of the reaction ensemble method outlined by Smith and applied to a reactive bromine/chlorine mixture. A very different phase transition - the liquid-solid transition - of water was the subject of a paper by Kusalik, in which the dynamical barriers to crystallization were overcome by the application of a large electric field (also known as electrofreezing). Forstmann and Levesque presented papers on phase transitions studied by integral equations and simulation. Voertler spoke on phase equilibria in aqueous systems (homogeneous and inhomogeneous) using the recently developed primitive models of water. Elliott described an alternative method for simulating phase equilibrium that involved using theory to describe the vapor phase; the method was applied to a fluid of bead-spring chain molecules in which the beads interact by square-well potentials.

In the final session of the conference, devoted to theory, Stell began the session with a review of recent advances on some long-standing problems in integral equation approaches to the theory of fluids. In particular, he described self-consistent integral equation theories which, as a result of self-consistency, exhibit improved behavior in the vicinity of the liquid-vapor critical point. Rickayzen and Borstnik presented papers on alternative approaches to the theory of molecular fluids. Henderson discussed the shortcomings of the Carnahan-Starling-Mansoori-Leland (CSML) equation of state for hard sphere mixtures in the case where one of the species has a large hard sphere diameter and is at extremely low concentration. He presented arguments to show that the CSML equation must predict unphysical behavior in this limit. Lee spoke on 'self-consistent' closures to the OZ relation (based on the Verlet closure) and demonstrated their accuracy for various hard sphere fluids.

In addition to the plenary lectures and contributed oral presentations, there was a poster session with 62 posters presenting new original results and new methods. Titles of the poster papers are provided at the conference web site, whose address is given in Section 1.

There will be a special issue of the Journal of Molecular Liquids (with guest editors H. Krienke and I. Nezbeda) publishing papers from the minisymposium on ionic systems.

As a result of a specific policy decision, no oral papers in the technical program were papers were presented by researchers from the host country, the Czech Republic, although many such papers were presented in the poster sessions. This unusual policy was designed to ensure that the conference did not become disproportionately focused on research from the Czech Republic.

The Fifth Liblice Conference on the Statistical Mechanics of Liquids demonstrated, yet again, the vitality and versatility of this field, covering wide variations in theory, simulation and experiment, and ranging from fundamental studies to very applied studies of systems of engineering interest. In fact, the Liblice conference dramatically reflected a growing trend in the liquids community in the U.S. - well over half of the U.S. academic participants have affiliations with chemical engineering departments, where the results of decades of liquid state research are today being applied to systems of industrial interest on an almost routine basis. Thus, in addition to fostering exchange between east and west, the Liblice conference can also lay claim to a significant role in fostering exchange between fundamental science and engineering application. We look forward with anticipation and enthusiasm to the Sixth Liblice Conference on the Statistical Mechanics of Liquids, to be held in 2002 in another (yet to be chosen) mountain resort in the Czech Republic.