ABINIT is a package whose main program allows one to find the total energy, charge density, electronic structure and many other properties of systems made of electrons and nuclei, (molecules and periodic solids) within Density Functional Theory (DFT), Many-Body Perturbation Theory (GW approximation and Bethe Salpeter equation) and Dynamical Mean Field Theory (DMFT). ABINIT also allows to optimize the geometry according to the DFT forces and stresses, to perform molecular dynamics simulations using these forces, and to generate dynamical matrices, Born effective charges and dielectric tensors. The present paper aims to describe the new capabilities of ABINIT that have been developed since 2009. It covers both physical and technical developments inside the ABINIT code, as well as developments provided within the ABINIT package. The developments are described with relevant references, input variables, tests and tutorials. (C) 2016 Elsevier B.V. All rights reserved.

Vibrational properties of solids can be efficiently computed in a framework that combines density-functional theory and perturbation theory, called density-functional perturbation theory (DFPT). Recently, we have formulated DFPT for the projector-augmented wave (PAW) methodology, and we present a brief account of this work. The large effect of spin-orbit coupling on vibrational properties of Bi, Pb, and lead chalcogenides (PbS, PbSe, and PbTe) is also presented.

We implemented the calculation of the transport properties within the PAW formalism in the ABINIT code [1]. This feature allows the calculation of the electrical and optical properties, including the XANES spectrum, as well as the electronic contribution to the thermal conductivity. We present here the details of the implementation and results obtained for warm dense aluminum plasma.

ABINIT [http://www.abinit.org] allows one to study, frorn first-principles, systems made of electrons and nuclei (e.g. periodic solids, molecules. nanostructures, etc.), on the basis of Density-Functional Theory (DFT) and Many-Body Perturbation Theory. Beyond the computation of the total energy, charge density and electronic structure of such systems, ABINIT also implements many dynamical, dielectric, thermodynamical, mechanical. or electronic properties, at different levels of approximation. The present paper provides an exhaustive account of the capabilities of ABINIT. It should be helpful to scientists that are not familiarized with ABINIT, as well as to already regular users. First, we give a broad overview of ABINIT, including the list of the capabilities and how to access them. Then, we present in more details the recent, advanced, developments of ABINIT, with adequate references to the underlying theory, as well as the relevant input variables, tests and, if available, ABINIT tutorials.Program summaryProgram title: ABINITCatalogue identifier: AEEU-v1-0Distribution fop-mat: tar.gzJoumal reference: Comput. Phys. Comm.Programming language: Fortran95, PERL scripts, Python scriptsComputer: All systems with a Fortran95 compilerOperating system: All systems with a Fortran95 compilerHas the code been vectorized or parallelized?: Sequential, or parallel with proven speed-up up to one thousand processors.RAM: Ranges from a few Mbytes to several hundred Gbytes, depending on the input file.Classification: 7.3. 7.8External routines: (all optional) BigDFT [1], ETSF 10 [2], libxc [3]. NetCDF [4], MPI [5], Wannier90 [6]Nature of problem: This package has the purpose of computing accurately material and nanostructure properties: electronic structure, bond lengths, bond angles, primitive cell size, cohesive energy, dielectric properties, vibrational properties, elastic properties, optical properties, magnetic properties, non-linear couplings, electronic and vibrational lifetimes, etc.Solution method: Software application based on Density-Functional Theory and Many-Body Perturbation Theory, pseudopotentials, with planewaves, Projector-Augmented Waves (PAW) or wavelets as basis functions.Running time: From less than one second for the simplest tests, to several weeks. The vast majority of the >600 provided tests run in less than 30 seconds.References:[1] http://inac.cea.fr/LSim/BigDFr.[2] http://etsLeu/index.php?page=standardization.[3] http://www.tddft.org/programs/octopus/wiki/index.php/Libxc.[4] http://www.uniciata.ucar.edti/software/iietcdL[5] http://en.wikipedia.org/wiki/MessagePassinginterface.[6] http://www.wannier.org. (C) 2009 Elsevier B.V. All rights reserved.

Exact (Hartree-Fock) exchange for correlated electrons is implemented to describe correlated orbitals in the projector augmented-waves (PAW) framework, as suggested recently in another context [P. Novaacutek , Phys. Status Solidi B 243, 563 (2006)]. Hartree-Fock exchange energy is applied to strongly correlated electrons only inside the PAW atomic spheres. This allows the use of PBE0 hybrid exchange-correlation functional for correlated electrons. This method is tested on NiO and results agree well with already published results and generalized gradient approximation, GGA+U calculations. It is then applied to plutonium oxides and UO2 for which the results are comparable with the ones of GGA+U calculations but without adjustable parameter. As evidenced in the uranium oxide case, the occurrence of multiple energy minima may lead to very different results depending on the initial electronic configurations and on the symmetries taken into account in the calculation.

In this paper, we present a study of the beta phase of cerium. We show that this is a correlated phase like gamma cerium. Their structural parameters and the antiferromagnetic ground state of beta Cerium are correctly described within the local density approximation with a Hubbard parameter U (LDA+U). We also discuss the problem of the search for the ground state of the system. The calculations are done within the projector augmented wave framework.

The description of realistic strongly correlated systems has recently advanced through the combination of density functional theory in the local density approximation (LDA) and dynamical mean field theory (DMFT). This LDA+DMFT method is able to treat both strongly correlated insulators and metals. Several interfaces between LDA and DMFT have been used, such as (N-th order) Linear Muffin Tin Orbitals or Maximally localized Wannier Functions. Such schemes are however either complex in use or additional simplifications are often performed (i.e., the atomic sphere approximation). We present an alternative implementation of LDA+DMFT, which keeps the precision of the Wannier implementation, but which is lighter. It relies on the projection of localized orbitals onto a restricted set of Kohn-Sham states to define the correlated subspace. The method is implemented within the Projector Augmented Wave (PAW) and within the Mixed Basis Pseudopotential (MBPP) frameworks. This opens the way to electronic structure calculations within LDA+DMFT for more complex structures with the precision of an all-electron method. We present an application to two correlated systems, namely SrVO3 and beta-NiS (a charge-transfer material), including ligand states in the basis-set. The results are compared to calculations done with Maximally Localized Wannier functions, and the physical features appearing in the orbitally resolved spectral functions are discussed.

In this paper, we present a study of the $\ensuremath{\beta}$ phase of cerium. We show that this is a correlated phase like $\ensuremath{\gamma}$ cerium. Their structural parameters and the antiferromagnetic ground state of $\ensuremath{\beta}$ Cerium are correctly described within the local density approximation with a Hubbard parameter $\text{U}\phantom{\rule{0.2em}{0ex}}(\text{LDA}+\text{U})$. We also discuss the problem of the search for the ground state of the system. The calculations are done within the projector augmented wave framework.

Phonon dispersion curves and thermodynamics of actinides are hardly accessible for both theory and experiments. In this paper we present an ab initio study of the thermodynamics properties of thorium within the framework of the quasiharmonic approximation and by using density-functional theory and the pseudopotential method. First we compare the phonon spectrum we obtained at zero pressure with inelastic neutron scattering experiments. Thereafter we use the phonon dispersions to obtain the PVT equations of state and derive thermodynamic quantities from the free energy. Then we compare our results for the thermal volume expansion, bulk modulus, heat capacity, or Debye temperature with experimental values when existing. The results show a promising agreement with experiment and propose several predictive behaviors.

A brief introduction to the ABINIT software package is given. Available under a free software license, it allows to compute directly a large set of properties useful for solid state studies, including structural and elastic properties, prediction of phase (meta)stability or instability, specific heat and free energy, spectroscopic and vibrational properties. These are described, and corresponding applications are presented. The emphasis is also laid on its ease of use and extensive documentation, allowing newcomers to quickly step in.

The density functional theory (DFT) computation of electronic structure, total energy and other properties of materials, is a field in constant progress. In order to stay at the forefront of knowledge, a DFT software project can benefit enormously from widespread collaboration, if handled properly. Also, modern software engineering concepts can considerably ease its development. The ABINIT project relies upon these ideas: freedom of sources, reliability, portability, and self-documentation are emphasised, in the development of a sophisticated plane-wave pseudopotential code. We describe ABINITv3.0, distributed under the GNU General Public License. The list of ABINITv3.0 capabilities is presented, as well as the different software techniques that have been used until now: PERL scripts and CPP directives treat a unique set of FORTRAN90 source files to generate sequential (or parallel) object code for many different platforms; more than 200 automated tests secure existing capabilities; strict coding rules are followed; the documentation is extensive, including online help files, tutorials, and HTML-formatted sources.

The results of first-principles density-functional calculations of the bulk moduli and related structural and electronic properties of all III-V and IV binary zinc-blende structures are presented. The band types and other properties for all the known materials in these two classes are correctly estimated. In studying the possibility to fabricate new materials, the results show that AlBi and TIP are direct band-gap semiconductors, while all the Pb-contained IV zinc-blende phases are conductors. The cell volume dependence of the bulk modulus for these phases is investigated. A linear relation between the bulk moduli and the inverse of unit-cell volumes, respectively, for IV and III-V zinc-blende phases is found. It is suggested that this linear relation arises from the same crystallographic configuration of IV and III-V zinc-blende phases.

A study on uranium and oxygen point defects in uranium dioxide using the ab initio plane-wave pseudopotential method in the local density approximation of the density functional theoretical framework is presented. Norm conserving pseudopotentials are used to describe oxygen and uranium atoms. The uranium pseudopotential is specifically described. Its validity is ascertained thanks to a detailed structural study of uranium dioxide and of three phases of metallic uranium (fcc, bcc, and a phase). The free energies of formation of both intrinsic (Frenkel pairs and Schottky defect) and extrinsic (single vacancies or interstitials) defects are calculated. The obtained values form a reliable set of numerical data that are analyzed in the framework of the point defect model which is commonly used to assess defect concentrations in uranium dioxide and their variation with stoichiometry. From the obtained results, the ability of the point defect model to accurately reproduce defect concentrations in uranium dioxide is discussed.

Equilibrium properties for the delta-phase of Pu have been calculated. Taking into account strong electron correlations in the 5f shell, we show how the equilibrium volume and the bulk modulus are improved in comparison to previous results using the local density approximation (LDA) or the generalized gradient approximation (GGA). In addition, an augmentation of the orbital moment is observed following Hund's rules, reducing the total magnetic moment. The stability of the delta-phase is explored and for the first time a positive value for the tetragonal shear constant is found.

The O K-edge x-ray absorption near-edge-structure (XANES) spectra of UO2 and CeO2 are presented and interpreted. Using different-size clusters around the excited atom in the full multiple-scattering (MS) simulation, we are able to link the features present in the spectra of each oxide to its specific atomic arrangement and electronic structure. The structures at the edge originate from oxygen 2p states hybridized with f and d orbitals of the cation split by the cubic crystal field. All of the other features come from MS with the neighbouring shells of the central oxygen atoms.

This study presents a comparison of the experimental O K-edge absorption spectrum of haematite (α-Fe2O3) with a theoretical spectrum obtained from all-electron ab initio periodic Hartree-Fock calculations of the antiferromagnetic R3 structure. There is good overall accord between the two spectra and agreement to within about 0.2eV for the major peak-to-peak separations. From a consideration of the empty p density of states (DOS), calculations predict the first 20eV of the absorption to result almost entirely from excitations of the type |O 1s⟩ → |O np⟩ with negligible participation of the Fe p states. The lower part of the spectrum is attributed to O p states hybridized with Fe d states while, at energies greater than 5eV above the absorption edge, in the region of the broad absorption at about 11 eV, calculations suggest that the predominant hybridization is with the Fe s states. Important differences are found between the near-edge empty p DOS of the antiferromagnetic R3 and ferromagnetic R3c spin orderings which suggests that spin-selective O K-edge spectra might be sensitive to the weak canting below the Morin temperature. The satisfactory agreement between experiment and theory, which is based on the calculated ground-state conduction band, confirms the view that core-hole states in charge-transfer insulators such as α-Fe2O3 are screened effectively by the valence electrons, which in these systems, are predominantly O in character.

Ce ions were implanted in Y2O3 Via x-ray absorption spectroscopy, Ce was found to occupy the Y site, and to be surrounded by oxygen atoms. However, contrary to what one would expect on the basis of this substitution, the oxidation state was not purely trivalent Thanks to the Anderson impurity model, it was possible to interpret the x-ray absorption features near the edge. Ce is found in an intermediate charge state resulting from the interaction of the f state with the valence band of Y2O3.

The electronic structure of empty states in quartz has been investigated by calculating the individual contributions of Si 1s, 2p and O 1s to the x-ray absorption near-edge structure (XANES) spectra; excellent agreement has been found between the experimental data and full multiple-scattering calculations. On the basis of the comparison, the origins of the spectral transition features can be assigned unambiguously. Although symmetry-based molecular-orbital theory is qualitatively adequate for describing these spectra, the interpretation of the Si K-edge XANES spectrum exclusively in terms of a ground-state potential is inappropriate in general.

The O K-edge x-ray absorption near edge structure (XANES) spectrum of is presented and interpreted. A comparison with that corresponding to is made. First-principles-based calculations using the LSDA+U approach allows us to link each feature present in the spectra to the specific atomic arrangement and electronic structure of the compound. The structures at the edge originate from oxygen 2p states hybridized with U 5f and 6d orbitals and the 6d splitting is found to be 4.8 eV. The structures due to O 2p - U 5f hybridization are found to be lower in energy than the structures due to the O 2p - U 6d hybridization. On this basis, can be considered as an f - f Mott - Hubbard insulator.