First-principles study of Ti-doped sodium alanate surfaces

We have performed first-principles calculations of thick slabs of Ti-doped sodium alanate (NaAlH_4), which allows to study the system energetics as the dopant progresses from the surface to the bulk. Our calculations predict that Ti stays on the surface, substitutes for Na, and attracts a large number of H atoms to its vicinity. Molecular dynamics simulations suggest that the most likely product of the Ti-doping is the formation of H-rich TiAl_n (n>1) compounds on the surface, and hint at the mechanism by which Ti enhances the reaction kinetics of NaAlH_4.Comment: 3 pages with 3 postscript figures embedded. Uses REVTEX4 and graphicx macros. More information at http://www.ncnr.nist.gov/staff/taner/alanates

Effective-Hamiltonian modeling of external pressures in ferroelectric perovskites

The phase-transition sequence of a ferroelectric perovskite such as BaTiO_3 can be simulated by computing the statistical mechanics of a first-principles derived effective Hamiltonian [Zhong, Vanderbilt and Rabe, Phys. Rev. Lett. 73, 1861 (1994)]. Within this method, the effect of an external pressure (in general, of any external field) can be studied by considering the appropriate "enthalpy" instead of the effective Hamiltonian itself. The legitimacy of this approach relies on two critical assumptions that, to the best of our knowledge, have not been adequately discussed in the literature to date: (i) that the zero-pressure relevant degrees of freedom are still the only relevant degrees of freedom at finite pressures, and (ii) that the truncation of the Taylor expansion of the energy considered in the effective Hamiltonian remains a good approximation at finite pressures. Here we address these issues in detail and present illustrative first-principles results for BaTiO_3. We also discuss how to construct effective Hamiltonians in cases in which these assumptions do not hold.Comment: 5 pages, with 2 postscript figures embedded. Proceedings of "Fundamental Physics of Ferroelectrics, 2002", R. Cohen and T. Egami, eds. (AIP, Melville, New York, 2002). Also available at http://www.physics.rutgers.edu/~dhv/preprints/ji_effp/index.htm

THE REDEFINITION OF THE MEXICAN STATE: ESSENTIAL PUBLIC POLICIES FOR THE DEVELOPMENT OF MEXICO

This paper draws on Iniguez-Montiel (2010, 2011a, 2014), providing a summary ofthe main research findings as well as making policy recommendations directly followingfrom them. Particularly, the study discusses the income-distributional andgrowth-enhancing policies that are required to create a virtuous cycle of inclusivedevelopment in Mexico. Moreover, it is argued that, for the Mexican economy todevelop and grow at considerably higher (potential) rates and, eventually, succeed inreducing and eradicating absolute poverty, the intervention of the state is indispensable.However, based on the successful experiences of the East-Asian economies (WorldBank, 1993) and an overall assessment of more than three decades of developmentoutcomes for Mexico as an open-market economy, the paper suggests the urgentredefinition of the Mexican state as an impartial referee that “leads the market” andlooks after the interests of the entire population, so that Mexico can grow at its fullpotential and a truly inclusive model could ever become part of the Mexican society

An empirical analysis of some underdevelopment issues facing the Mexican economy under its current development model

筑波大学University of Tsukuba博士（経済学）Doctor of Economics2011【要旨】thesi