70,992 research outputs found
Workshop report. Linear-Scaling Ab Initio Calculations: Applications and Future Directions
No full textThe study of properties and of processes in materials, frequently hinges upon understanding phenomena which originate at the atomic level. In such cases the accurate description of the interactions between large numbers of atoms is critical and in turn requires the accurate description of the electrons which play a crucial role in the bonding of atoms into molecules, surfaces and solids. This can only be achieved by solving the equations of quantum mechanics. These
equations are too complicated to solve exactly; however their solutions can be approximated by computational techniques. The most accurate ? but also most computationally demanding ? are the “ab initio” techniques which do not use any empirical adjustable parameters. Amongst them, the Density Functional Theory (DFT) formulation of quantum mechanics stands out as an excellent compromise between accuracy and computational efficiency. However, the applicability of ab initio techniques is severely limited by poor scaling: the computational effort needed to perform an ab initio calculation increases with (at least) the third power of the number of atoms, N. This cubic-scaling bottleneck limits the number of atoms we can study to a few hundred at most, even on parallel supercomputers. To overcome this length-scale limitation, a number of researchers worldwide have been pioneering the development of a novel class of ab initio methods with linear-scaling or “Order N” (O(N)) computational cost which nevertheless retain the same high level of accuracy as the conventional approaches. While physically motivated, such methods have proved particularly hard to develop as they introduce highly non-trivial localisation constraints. Nevertheless, many major obstacles have been overcome and a number of O(N)
methods (SIESTA, CONQUEST, ONETEP, etc.) for ground state DFT calculations on systems with a gap (e.g. molecules, semiconductors and insulators) are now available and have reached a state of maturity that allows them to be used to study ”real” materials. The particular focus of this workshop is therefore to look forward to what can be achieved in the next few years. Our aim is twofold: (1) As O(N) methods are currently extending the applicability of DFT calculations
to problems involving biomolecules and nanostructures they are leading to completely new levels of understanding of these systems. This CECAM meeting will give us the opportunity to make an appraisal of such large-scale simulations and their potential to connect more directly to experiments. (2) We also want to examine the options for extending linear-scaling to problems that cannot be treated by ground-state DFT but require other, more complex approaches. These include methods for treating metallic systems, excited states and wavefunction-based theories for including electronic correlation. Finding ways to transform these methods to linear-scaling
cost, and hence extent their applicability to the nano-scale, is the next big challenge that the community of developers of large-scale electronic structure methods is beginning to face. We
hope that this workshop will stimulate these major new O(N) methodological developments by bringing together the leading groups in the development of O(N) DFT methods with the leading
groups in the development of metal and excited-state or wavefunction-based methods. Strong emphasis during the workshop will be given to discussion in order to promote the exchange
of ideas between different communities (Physics, Chemistry, Materials Science, Biochemistry) which are all interested in large-scale applications with ab initio accuracy but are approaching
them from different perspectives
Antiatherosclerotic effect of the new Ca++ antagonist sim 6080: "In vitro" and "In vivo studies
No full textDisplay At Your Own Risk: An experimental exhibition of digital cultural heritage
No full textA research-led exhibition experiment concerned with the use and reuse of digital surrogates of public domain works of art produced by cultural heritage institutions of international repute.This publication is issued in conjunction with the exhibition Display At Your Own Risk, held at The Lighthouse in Glasgow and made available as an open source exhibition at displayatyourownrisk.org. The print exhibition is on view in Glasgow on 8 June 2016.This research project is funded by CREATe, University of Glasgow (under a joint grant from Arts and Humanities Research Council AHRC, Economic and Social Research Council ESRC and Engineering and Physical Sciences Research Council EPSRC).
The exhibition is supported in part by the National Library of Scotland, the Glasgow Print Studio and the Glasgow University Archive Services. Print services for the exhibition were provided by the National Library of Scotland and the Glasgow Print Studio; digitization services were provided by the University of Glasgow Photographic Unit within the Glasgow University Archive Services
Ligand binding by r<i>Ab</i>-FAR-1.
No full text<p><b>(A)</b><i>Ab</i>-FAR-1. The reverse change of DAUDA emission was observed after the addition of oleic acid to the r<i>Ab</i>-FAR-1+DAUDA complex. The wavelengths of peak emission by DAUDA were different. <b>(B)</b> Fluorescence emission spectra (excitation at 350 nm) of retinol in ethanol alone or after the addition of r<i>Ab</i>-FAR-1. The competitive effect of oleic acid was also found. <b>(C)</b> Fluorescence emission spectra (excitation at 319 nm) of cis-parinaric acid alone or after the addition of r<i>Ab</i>-FAR-1.The effects of the subsequent addition of retinol to the r<i>Ab</i>-FAR-1+cis-parinaric acid and addition of oleic acid solution to the r<i>Ab</i>-FAR-1+cis-parinaric acid+ retinol were examined.</p
Ab initio simulations of iron-nickel alloys at Earth's core conditions
No full textWe report ab initio density functional theory calculations on iron–nickel (FeNi) alloys at conditions representative of the Earth's inner core. We test different concentrations of Ni, up to ∼39 wt% using ab initio lattice dynamics, and investigate the thermodynamic and vibrational stability of the three candidate crystal structures (bcc, hcp and fcc). First of all, at inner core pressures, we find that pure Fe transforms from the hcp to the fcc phase at around 6000 K. Secondly, in agreement with low pressure experiments on Fe–Ni alloys, we find the fcc structure is stabilised by the incorporation of Ni under core pressures and temperatures. Our results show that the fcc structure may, therefore, be stable under core conditions depending on the temperature in the inner core and the Ni content. Lastly, we find that within the quasi-harmonic approximation, there is no stability field for FeNi alloys in the bcc structure under core conditions
Reduced dimensionality spin-orbit dynamics of CH3 + HCl reversible arrow CH4 Cl on ab initio surfaces
No full textA reduced dimensionality quantum scattering method is extended to the study of spin-orbit nonadiabatic transitions in the CH3 + HCl reversible arrow CH4 + Cl(P-2(J)) reaction. Three two-dimensional potential energy surfaces are developed by fitting a 29 parameter double-Morse function to CCSD(T)/IB//MP2/cc-pV(T+d)Z-dk ab initio data; interaction between surfaces is described by geometry-dependent spin-orbit coupling functions fit to MCSCF/cc-pV(T+d)Z-dk ab initio data. Spectator modes are treated adiabatically via inclusion of curvilinear projected frequencies. The total scattering wave function is expanded in a vibronic basis set and close-coupled equations are solved via R-matrix propagation. Ground state thermal rate constants for forward and reverse reactions agree well with experiment. Multi-surface reaction probabilities, integral cross sections, and initial-state selected branching ratios all highlight the importance of vibrational energy in mediating nonadiabatic transition. Electronically excited state dynamics are seen to play a small but significant role as consistent with experimental conclusions. (C) 2011 American Institute of Physics. [doi:10.1063/1.3592732]</p
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
[print] [Portret van Marcus ab Aviano] /
No full textOpschrift: Vera effigies R. P. Marci ab Aviano f.f. Capvcinorvm Prædicatores ætatisEuropeana-GoogleBook
R. P. R. Souarn, ex augustinianis ab Aseumptione. Praxis missionarii in Oriente servata
No full textCatoire A. R. P. R. Souarn, ex augustinianis ab Aseumptione. Praxis missionarii in Oriente servata. In: Échos d'Orient, tome 14, n°89, 1911. pp. 251-252
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