“Liquids, Crystals, Liquid Crystals, Plastic Crystals, & More ...”
My talk will first review the states of matter accessible to condensed phase systems. Atomic solids typically exhibit three phases: long-range center-of-mass order (conventional solid), plus disordered liquid or glass phases. Molecular systems, on the other hand, have orientational (and internal) degrees of freedom, which introduce additional possibilities, even for small rigid molecules such as, CH4, CCl4, O2, and CH3OH.
Molecules with internal degrees of freedom and/or flexibility, such as, surfactants, lipids, dendrimers, peptides, or even proteins, self-assemble into an array of distinct condensed phases. Using selective examples, the talk will survey some of the intriguing phases exhibited by Nature.
“Role of Reaction Dynamics and Surface Topology in Enzymatic Catalysis”
“All-atom DFT simulation of charged metaloxide-electrolyte interfaces”
Fully atomistic (all-atom) modelling of metal-oxides electrolyte interfaces treating the aqueous solution (electrolyte) at the same level of Density Functional Theory (DFT) remains a challenge. An obvious problem is that the periodic boundary conditions applied in DFTMD force us to use a slab geometry with two interfaces. Moreover, it would be better if an interface could be charged at fixed composition. Changes in the number of particles are better avoided in DFT. This is why we have opted for a method for charging the two interfaces by transferring charge (protons for example) from one side of the slab to the other leading to surfaces of opposite charge. The drawback is that this creates a large electric field inside the solid slab if the metal oxide is an insulator making a very poor model for an interface of a semi-infinite solid. In a recent simulation of a classical spc force field model of a charged interface we have shown how this difficulty can be overcome using finite electric field methods. The DFTMD implementation of the finite field method was validated in a computation of the static dielectric constant of PBE water. In this talk we will outline the development of the method and report on the first DFT application to a model TiO2 electrolyte interface (2M NaCl). We end with an outlook for the investigation of polar surfaces in contact with an electrolyte.
- Chao Zhang and Michiel Sprik, Phys. Rev. B 94 (2016), 245309.
- Chao Zhang, Juerg Hutter, and Michiel Sprik, J. Phys. Chem. Lett. 7 (2016), 2696.