Showing papers by "Paolo Giannozzi published in 2009"

QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials

Abstract: QUANTUM ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). The acronym ESPRESSO stands for opEn Source Package for Research in Electronic Structure, Simulation, and Optimization. It is freely available to researchers around the world under the terms of the GNU General Public License. QUANTUM ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively parallel architectures, and a great effort being devoted to user friendliness. QUANTUM ESPRESSO is evolving towards a distribution of independent and interoperable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.

Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials

Abstract: Quantum ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). Quantum ESPRESSO stands for "opEn Source Package for Research in Electronic Structure, Simulation, and Optimization". It is freely available to researchers around the world under the terms of the GNU General Public License. Quantum ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively-parallel architectures, and a great effort being devoted to user friendliness. Quantum ESPRESSO is evolving towards a distribution of independent and inter-operable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.

Gas adsorption on graphene doped with B, N, Al, and S: A theoretical study

Abstract: The adsorption of several common gas molecules over boron-, nitrogen-, aluminum-, and sulfur-doped graphene was theoretically studied using density-functional theory. B- and N-doped graphene retain a planar form, while Al and S atoms protrude out of the graphene layer. We find that only NO and NO2 bind to B-doped graphene, while only NO2 binds to S-doped graphene. Al-doped graphene is much more reactive and binds many more gases, including O2. We suggest that B- and S-doped graphene could be a good sensor for polluting gases such as NO and NO2.

Thermal properties of materials from ab-initio quasi-harmonic phonons

Abstract: This paper gives a short overview of the calculation of thermal properties of materials from first principles, using the Quasi-Harmonic Approximation (QHA) We first introduce some of the thermal properties of interest and describe how they can be calculated in the framework of the QHA; then we briefly recall Density-Functional Perturbation Theory as a tool for calculating phonons from first principles, and present some codes that implement it; finally we review recent applications of first-principle QHA

Ab initio Theoretical Investigation of Phthalocyanine−Semiconductor Hybrid Systems

Abstract: In the present study, an extensive investigation of the molecule−surface interaction in hybrid systems formed by phthalocyanines (Pcs) and inorganic semiconductors (IS) has been performed by using ...

Large-scale computing with Quantum ESPRESSO

Abstract: Quantum ESPRESSO (QE) starts in 2002 as a DEMOCRITOS initiative, in collaboration with SISSA, CINECA and with research groups in Princeton University, MIT, EPF Lausanne [1]. The name “ESPRESSO” stands for opEn Source Package for Research in Electronic Structure, Simulation, and Optimization, while “Quantum” stresses its scope: first-principle (i.e. based on the electronic structure) calculations within DensityFunctional Theory (DFT) in a plane-wave (PW) pseudopotential (PP) approach. Building upon pre-existing codes, QE is evolving into a distribution, open to external contributions: QE is released under the terms of the General Public License (GPL). Different categories of scientists may find QE useful for their research work:

Ab initio molecular dynamics study of amorphous CdTeOx alloys: Structural properties

Abstract: The structural short-range order of amorphous compounds with the composition CdTeOx a-CdTeOx is investigated by means of ab initio molecular dynamics The interatomic forces have been calculated using a plane-wave pseudopotential implementation of density-functional theory Molecular dynamics has been performed in the nearly-microcanonical ensemble using the Berendsen algorithm to keep the systems at the desired temperature The compounds are characterized using the pair distribution functions, angle distribution functions, coordination numbers, histograms of coordination numbers, and a description of the molecular units of the compounds According to our simulations, a-CdTeO and a-CdTeO2 are more disordered than a-CdTeO02 and a-CdTeO3 I na-CdTeO02, the most abundant clusters are TeCd4, CdTe4, TeCd3, and CdTe3O In the case of a-CdTeO and a-CdTeO2, having structural units of types similar to those found in crystalline phases of the Cd-Te-O system, they show no predominant type of cluster This absence of predominant building blocks is a signature of chemical disorder, and it seems that Te and O atoms can be freely exchanged, as well as Cd to a lesser extent Finally, in a-CdTeO3, the most abundant clusters are CdO6, CdO5, TeO3, and TeO4