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The Abdus Salam International Centre for Theoretical Physics (ICTP)

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2017 · Journal of Physics Condensed Matter · 7,665 citations

Advanced capabilities for materials modelling with Q <scp>uantum</scp> ESPRESSO

Quantum EXPRESSO is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the-art electronic-structure techniques, based on density-functional theory, density-functional perturbation theory, and many-body perturbation theory, within the plane-wave pseudopotential and projector-augmented-wave approaches. Quantum EXPRESSO owes its popularity to the wide variety of properties and processes it allows to simulate, to its performance on an increasingly broad array of hardware architectures, and to a community of researchers that rely on its capabilities as a core open-source development platform to implement their ideas. In this paper we describe recent extensions and improvements, covering new methodologies and property calculators, improved parallelization, code modularization, and extended interoperability both within the distribution and with external software.

2016 · International Journal of Climatology · 69 citations

Multi‐model <scp>CMIP5</scp> and <scp>CORDEX</scp> simulations of historical summer temperature and precipitation variabilities over West Africa

ABSTRACT The mean climatology, inter‐model variability and spatio‐temporal patterns of temperature and precipitation over West Africa from Coupled Model Intercomparison Project 5 ( CMIP5 ), CMIP5_SUBSET [ensemble of global climate models driving COordinated Regional climate Downscaling EXperiment ( CORDEX )] and CORDEX multi‐model ensembles are evaluated and intercompared for the monsoon season (June–September). We find that, while CORDEX fails to outperform the simulated mean climatology of temperature by the CMIP5 ensembles, it substantially improves precipitation and provides more realistic fine‐scale features tied to local topography and landuse. This improved performance over the region is found to depend more on the internal models physics than the driving boundary conditions and results from a more consistent and realistic simulation of monsoon precipitation across the various regional climate models ( RCMs ). Rotated empirical orthogonal function ( REOF ) analysis indicates that the CORDEX ensemble captures better the spatio‐temporal variability of both temperature and precipitation (first REOF mode), in particular depicting the warming and Sahel precipitation recovery in recent decades over West Africa. On the other hand, the spatial patterns and associated time series of the last two REOF modes in CORDEX mostly follow the CMIP5_SUBSET pointing towards a strong role of the boundary forcing in the RCM simulation of precipitation variability.

2009 · South African Journal of Geology · 18 citations

DETERMINISTIC SEISMIC GROUND MOTION MODELLING OF THE GREATER ACCRA METROPOLITAN AREA, SOUTHEASTERN GHANA

Research Article| December 01, 2009 DETERMINISTIC SEISMIC GROUND MOTION MODELLING OF THE GREATER ACCRA METROPOLITAN AREA, SOUTHEASTERN GHANA P.E. AMPONSAH; P.E. AMPONSAH Geological Survey Department, Accra, Ghana, e-mail: pekua2@yahoo.com Search for other works by this author on: GSW Google Scholar B.K. BANOENG-YAKUBO; B.K. BANOENG-YAKUBO Geology Department, University of Ghana, Legon, Ghana, e-mail: bbruce@ug.edu.gh Search for other works by this author on: GSW Google Scholar G.F. PANZA; G.F. PANZA Department of Earth Sciences, University of Trieste, Italy, The Abdus Salam International Centre for Theoretical Physics- ESP SAND group, Trieste, Italy, e-mail: panza@dst.units.it Search for other works by this author on: GSW Google Scholar F. VACCARI F. VACCARI Department of Earth Sciences, University of Trieste, Italy, e-mail: vaccari@dst.units.it Search for other works by this author on: GSW Google Scholar Author and Article Information P.E. AMPONSAH Geological Survey Department, Accra, Ghana, e-mail: pekua2@yahoo.com B.K. BANOENG-YAKUBO Geology Department, University of Ghana, Legon, Ghana, e-mail: bbruce@ug.edu.gh G.F. PANZA Department of Earth Sciences, University of Trieste, Italy, The Abdus Salam International Centre for Theoretical Physics- ESP SAND group, Trieste, Italy, e-mail: panza@dst.units.it F. VACCARI Department of Earth Sciences, University of Trieste, Italy, e-mail: vaccari@dst.units.it Publisher: Geological Society of South Africa First Online: 09 Mar 2017 Online ISSN: 1996-8590 Print ISSN: 1012-0750 © 2009 Geological Society of South Africa South African Journal of Geology (2009) 112 (3-4): 317–328. https://doi.org/10.2113/gssajg.112.3-4.317 Article history First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation P.E. AMPONSAH, B.K. BANOENG-YAKUBO, G.F. PANZA, F. VACCARI; DETERMINISTIC SEISMIC GROUND MOTION MODELLING OF THE GREATER ACCRA METROPOLITAN AREA, SOUTHEASTERN GHANA. South African Journal of Geology 2009;; 112 (3-4): 317–328. doi: https://doi.org/10.2113/gssajg.112.3-4.317 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySouth African Journal of Geology Search Advanced Search Abstract The seismic ground motion of the greater Accra Metropolitan Area has been modelled for land use planning and disaster mitigation. The deterministic computation, a hybrid method based on the modal summation and finite difference method was used. Using these techniques, the seismic ground motion along four profiles located in the metropolis has been computed. The 1939 earthquake of magnitude 6.5 (ML ) was used as the scenario earthquake. Synthetic seismic waveforms from which parameters for engineering design such as peak ground acceleration, velocity and spectral amplifications have been produced along the geological cross sections. The peak ground acceleration and velocity computed for the metropolis ranges from 0.14 g to 0.57 g and 9.2 cms−1 to 37.1 cms−1, respectively. These correspond to intensity ranging from VII to IX on the Modified Mercalli Intensity scale. Areas in the metropolis underlain by unconsolidated sediments experience the largest shakings. The results illustrated represent a useful guide for civil engineers in the design of buildings in the metropolis for safe and sustainable development. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

2022 · Physical review. B./Physical review. B · 9 citations

Electronic structure and magnetism of the triple-layered ruthenate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Sr</mml:mi><mml:mn>4</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">Ru</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>10</mml:mn></mml:msub></mml:math>

We report electronic band structure calculations for ${\mathrm{Sr}}_{4}{\mathrm{Ru}}_{3}{\mathrm{O}}_{10}$ which display both ferromagnetic and metamagnetic behavior. The density functional calculations find the ground state to be ferromagnetic in agreement with experiment and we show that the resulting spin polarization has dramatic consequences for the electronic properties. The minority-spin bands are mainly empty and disperse steeply upward at the Fermi energy, whereas the majority-spin bands are full or nearly fully occupied and form narrow bands near the Fermi energy, which could be the electronic origin of the metamagnetism. Inclusion of a Hubbard interaction $U$ applied to the Ru $4d$ states has major effects on the narrow bands, which reveal the role of Coulomb interactions and correlated many-body physics. The results are in qualitative agreement with recent angle-resolved photoemission spectroscopy (ARPES) experiments and show the need for a combined theoretical study and experimental ARPES investigation with better energy resolution to reveal the nature of the narrow bands close to the Fermi level, which is critical for understanding the exotic magnetic properties observed in this material.