The size-modified Poisson-Boltzmann (MPB) equation is an efficient implicit solvation model which also captures electrolytic solvent effects. It combines an account of the dielectric solvent response with a mean-field description of solvated finite-sized ions. We present a general solution scheme for the MPB equation based on a fast function-space-oriented Newton method and a Green's function preconditioned iterative linear solver. In contrast to popular multigrid solvers, this approach allows us to fully exploit specialized integration grids and optimized integration schemes. We describe a corresponding numerically efficient implementation for the full-potential density-functional theory (DFT) code FHI-aims. We show that together with an additional Stern layer correction the DFT+MPB approach can describe the mean activity coefficient of a KCl aqueous solution over a wide range of concentrations. The high sensitivity of the calculated activity coefficient on the employed ionic parameters thereby suggests to use extensively tabulated experimental activity coefficients of salt solutions for a systematic parametrization protocol.

In computer simulations of solvation effects on chemical reactions, continuum modeling techniques regain popularity as a way to efficiently circumvent an otherwise costly sampling of solvent degrees of freedom. As effective techniques, such implicit solvation models always depend on a number of parameters that need to be determined earlier. In the past, the focus lay mostly on an accurate parametrization of water models. Yet, non-aqueous solvents have recently attracted increasing attention, in particular, for the design of battery materials. To this end, we present a systematic parametrization protocol for the Self-Consistent Continuum Solvation (SCCS) model resulting in optimized parameters for 67 non-aqueous solvents. Our parametrization is based on a collection of ≈6000 experimentally measured partition coefficients, which we collected in the Solv@TUM database presented here. The accuracy of our optimized SCCS model is comparable to the well-known universal continuum solvation model (SMx) family of methods, while relying on only a single fit parameter and thereby largely reducing statistical noise. Furthermore, slightly modifying the non-electrostatic terms of the model, we present the SCCS-P solvation model as a more accurate alternative, in particular, for aromatic solutes. Finally, we show that SCCS parameters can, to a good degree of accuracy, also be predicted for solvents outside the database using merely the dielectric bulk permittivity of the solvent of choice.

The Green Biorefi nery (GBR) is a complex and full-integrated system of environment-and resource-protecting technologies for comprehensive material and energetic use of green biomasses. GBR's are multiproduct systems and perform and produce in accordance with the physiology of the corresponding plant material preserving and using the diversity of the synthesis generated by nature. In addition to the general biorefi nery concept, GBR's are based strongly on sustainable principles (sustainable land use, sustainable raw materials, gentle technologies, autarkic energy supply, etc.). Existing agricultural structures of the green crop processing industry, such as green crop drying plants, offer good opportunities for the implementation of biorefi nery technologies that will help overcoming energy-intensive and partially obsolete technologies, such as the thermal drying of feedstock. Accordingly, the primary fractionation of green biomasses and the integrated production of proteins, fermentation media, animal feed, and biogas was projected and will be realized in a demonstration facility directly linked to the existing green crop drying plant, Selbelang, in Havelland (Germany, state Brandenburg, 50 km west of Berlin). The primary refi nery will have an annual capacity of 20 000 tons alfalfa and grass biomass and can be diversifi ed in modules for the production of platform chemicals and synthesis gas.We discuss the processes, products, operating costs and climate protection effects through examination of the basic engineering of the primary refi nery. The production site and planned demonstration facility are also presented.