Ab initio atomistic thermodynamics and statistical mechanics of surface properties and functions

Previous and present "academic" research aiming at atomic scale understanding is mainly concerned with the study of individual molecular processes possibly underlying materials science applications. Appealing properties of an individual process are then frequently discussed in terms of their direct importance for the envisioned material function, or reciprocally, the function of materials is somehow believed to be understandable by essentially one prominent elementary process only. What is often overlooked in this approach is that in macroscopic systems of technological relevance typically a large number of distinct atomic scale processes take place. Which of them are decisive for observable system properties and functions is then not only determined by the detailed individual properties of each process alone, but in many, if not most cases also the interplay of all processes, i.e. how they act together, plays a crucial role. For a "predictive materials science modeling with microscopic understanding", a description that treats the statistical interplay of a large number of microscopically well-described elementary processes must therefore be applied. Modern electronic structure theory methods such as DFT have become a standard tool for the accurate description of individual molecular processes. Here, we discuss the present status of emerging methodologies which attempt to achieve a (hopefully seamless) match of DFT with concepts from statistical mechanics or thermodynamics, in order to also address the interplay of the various molecular processes. The new quality of, and the novel insights that can be gained by, such techniques is illustrated by how they allow the description of crystal surfaces in contact with realistic gas-phase environments.Comment: 24 pages including 17 figures, related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

The impact of government decentralization on county health spending for the uninsured in California

We analyze Program Realignment, California’s 1991 policy of decentralizing control of health, mental health, and social services, from the state to the counties. Drawing from the economics literature on intergovernmental transfers and using data constructed for this study, we analyze the impact of Realignment on uninsured health spending. We find a change in the pattern of spending on indigent health services by counties following decentralization. Our results suggest, however, that county-level governments maintain a level of commitment to social-service spending that recent studies indicate may be lacking at the state level. Copyright Springer Science+Business Media, LLC 2006Federalism, State and local budget and expenditures, Public health, H72, H77, I18,