@article{bock_gubbins_schoen_2007, title={Anisotropic self-diffusion in nanofluidic structures}, volume={111}, ISSN={["1932-7455"]}, DOI={10.1021/jp071861y}, abstractNote={By means of equilibrium molecular dynamics simulations, we investigate self-diffusion in a “simple” fluid confined to nanoscopic slit-pores. The pore walls are decorated with wettable and nonwettable chemical “stripes” that alternate in the x direction and are assumed infinitely long in the y direction. We consider the impact of pore width as well as variations of the width of the wettable stripes dwet. Depending on these model parameters and the thermodynamic conditions, the confined fluid may exist as one of three morphologically distinct phases:  a thin fluid film adsorbed by the wettable stripes, a fluid bridge spanning the gap between the (aligned) stripes on the two opposite substrates, or a nanostructured liquid where molecules occupy the entire space between the substrate surfaces. By analyzing mean square displacements, velocity autocorrelation functions, and their power spectra, a detailed picture of mass transport and its relation to substrate decoration emerges. In particular, we find that the...}, number={43}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Bock, Henry and Gubbins, Keith E. and Schoen, Martin}, year={2007}, month={Nov}, pages={15493–15504} }
 @article{bock_gubbins_klapp_2007, title={Coarse graining of nonbonded degrees of freedom}, volume={98}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.98.267801}, abstractNote={We investigate the physical meaning of coarse-grained beads generated by coarse graining of nonbonded particles such as solvent molecules in a solution. Starting from the partition function, we analytically coarse grain an N-particle fluid to a system containing N-2 of the original particles plus a bead representing the two remaining particles. As a direct consequence of the lack of bonding interactions, the resulting effective potential becomes independent of the bead coordinates, i.e., ideal-gas-like, in the thermodynamic limit. Thus, there are no conservative forces between coarse-grained beads representing assemblies of nonbonded molecules nor between these beads and any other species in the system.}, number={26}, journal={PHYSICAL REVIEW LETTERS}, author={Bock, H. and Gubbins, K. E. and Klapp, S. H. L.}, year={2007}, month={Jun} }
 @article{dietsch_eltekov_bock_gubbins_findenegg_2007, title={Crossover from normal to inverse temperature dependence in the adsorption of nonionic surfactants at hydrophilic surfaces and pore walls}, volume={111}, ISSN={["1932-7455"]}, DOI={10.1021/jp0747656}, abstractNote={The adsorption of the nonionic surfactant C8E4 from its aqueous solutions to the pore walls of four controlled-pore silica glass (CPG) materials of different mean pore widths (10−50 nm) has been studied in a temperature range from 5 to 45 °C, that is, close to the lower critical temperature of liquid−liquid phase separation of the bulk system (Tc ≈ 40 °C). Pronounced S-shaped isotherms, with a normal temperature dependence of the adsorption in the initial low-affinity region but an inverse temperature dependence in the plateau region, are found with all CPG materials. The experimental adsorption isotherms are compared with predictions of a theoretical model (Phys. Rev. Lett. 2004, 92, 135701), which takes into account H-bonding and micelle formation in the bulk and at the surface. It is found that this model reproduces all peculiarities of the adsorption in the present systems. The following conclusions emerge from this analysis:  (1) At low bulk concentrations, the surfactant is adsorbed only in monomeri...}, number={43}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Dietsch, Oliver and Eltekov, Anton and Bock, Henry and Gubbins, Keith E. and Findenegg, Gerhard H.}, year={2007}, month={Nov}, pages={16045–16054} }
 @article{chennamsetty_bock_gubbins_2005, title={Coarse-grained potentials from Widom's particle insertion method}, volume={103}, ISSN={["1362-3028"]}, DOI={10.1080/00268970500208658}, abstractNote={Widom's particle insertion method is used to calculate effective pair potentials for binary A/B mixtures, where B molecules represent a solvent whose degrees of freedom are integrated out. Comparison of Widom's method with an alternative route via the potential of mean force shows good agreement; however, Widom's particle insertion method experiences sampling difficulties at high densities. An isotherm for a binary mixture of argon (‘solvent’, B) and krypton (‘solute’, A) is calculated. While the structure at the pair level is well represented by the effective system using only effective pair potentials and ignoring all higher multi-body contributions, increasing deviations in the pressure are observed as the density of the effective system is increased. These latter deviations are attributed to the neglect of three- and higher multi-body interactions.}, number={21-23}, journal={MOLECULAR PHYSICS}, author={Chennamsetty, N and Bock, H and Gubbins, KE}, year={2005}, pages={3185–3193} }
 @article{chennamsetty_bock_scanu_siperstein_gubbins_2005, title={Cosurfactant and cosolvent effects on surfactant self-assembly in supercritical carbon dioxide}, volume={122}, ISSN={["1089-7690"]}, DOI={10.1063/1.1855291}, abstractNote={The impact of alcohol additives on the self-assembly of surfactants in supercritical carbon dioxide is investigated using lattice Monte Carlo simulations. We observe that all studied (model) alcohols reduce the critical micelle concentration. The reduction is stronger the longer the hydrocarbon chain of the alcohol, and the higher the alcohol concentration. Short-chain alcohols are found to concentrate in the surfactant layer of the aggregates, replacing surfactant molecules and leading to a strong decrease of the aggregation number and a large increase of the number of aggregates. On the other hand, only a small number of alcohol molecules with longer chain length are found in the aggregates, leading to a slight increase in the aggregation number. However, structural properties such as size and density profiles of aggregates at the same aggregation number are not influenced markedly. Consequently, short-chain alcohols act as cosurfactants, directly influencing the properties of the aggregates, while alcohols with longer hydrocarbon chains work as cosolvents, altering the properties of the solvent. However, the transition between both extremes is gradual.}, number={9}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Chennamsetty, N and Bock, H and Scanu, LF and Siperstein, FR and Gubbins, KE}, year={2005}, month={Mar} }
 @article{bock_gubbins_ayappa_2005, title={Solid/solid phase transitions in confined thin films: A zero temperature approach}, volume={122}, ISSN={["1089-7690"]}, DOI={10.1063/1.1856921}, abstractNote={We report a density functional theory study of confinement induced solid/solid phase transitions in a thin film (modeled as methane) at T=0. The solid film is confined by two graphite surfaces represented by a mean-field potential. As the wall separation is varied the structure of the confined film changes, which influences its density and the solvation force. Using the directly accessible grand canonical potential density we determine the stable phases and calculate the exact location of the phase transitions. We observe a series of phases having square and triangular symmetry. At low wall separations we find zig-zag buckling and an asymmetric buckled phase, whose structure is consistent with the strongest buckling instability of a triangular monolayer predicted by Chou and Nelson [Phys. Rev. E 48, 4611 (1993)] but, to our knowledge, has not been observed as a stable phase before. We find that the two-dimensional order parameters Psi(4) (square symmetry) and Psi(6) (triangular symmetry) show unphysical behavior in the transition region between square and triangular symmetry. Thus, in the present model they fail to predict the right location of the phase transitions.}, number={9}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Bock, H and Gubbins, KE and Ayappa, KG}, year={2005}, month={Mar} }