Welcome¶
Overview of the ABINIT tutorials.¶
These tutorials are aimed at teaching stepbystep the use of ABINIT, in the UNIX/Linux OS and its variants (MacOS, AIX etc.). They might be used for other operating systems, but the commands have to be adapted.
At present, more than forty tutorials are available. Each of them is at most two hours of student work. The set of tutorials is more structured and gradual than the user guides, but one need to invest more time to read them.
Dependencies between tutorials are present. To start with, four tutorials cover the basics of using ABINIT, and one tutorial explains in detail the build of ABINIT (as a complement to the easier user guide type documentation). Six tutorials are intermediate level ones, that might be prerequisite for some more advanced tutorials. The following schema should help to understand these dependencies. To access the tutorials, see the menu on the left…
The four basic tutorials are presented at the top, in one orange block. There is also an orange block for the ABINIT_build tutorial. Each block in brown represents one intermediatelevel tutorial. The blocks in red gather by themes one block per theme the more advanced tutorials. The following themes are covered: ABINIT postprocessors, static DFT, ManyBody Theory and excitations, DensityFunctional Perturbation Theory DFPT and electronphonon interaction, multiscale calculations with MULTIBINIT, and parallelism. See the list of acronyms.
The basic tutorials are prerequisite for all other tutorials, as represented by the heavy orange arrows. Then, some relationships between intermediatelevel and advancedlevel tutorials are indicated, in brown. A heavy brown arrow indicates that the starting intermediate tutorial is mandatory for all the tutorials of the indicated theme, while a dashed brown arrow indicates that only some of the tutorials of the indicated theme will need it.
Inside a theme, there are also subsets of tutorials indicated with a light contour. They are logically related to each other, and usually to be done one after the other. Otherwise, advanced tutorials usually do not have mutual dependencies. There are however three exceptions: the GW1 tutorial is a prerequisite for the paral_MBPT tutorial, the parallelism tutorial is a prerequisite for the LRUJ tutorial, while the lattice_wannier tutorial is a prerequisite for the lwf_model tutorial.
Visualisation tools are NOT covered in the ABINIT tutorials. Powerful visualisation procedures have been developed in the Abipy context, relying on matplotlib. See the README of Abipy and the Abipy tutorials.
Before following the tutorials, you should have read the new user’s guide, as well as the pages 10451058 of Rev. Mod. Phys. 64, 1045 (1992). If you have more time, you should browse through the Chaps. 1 to 13, and appendices L and M of the book this book by R. M. Martin. Alternatively, the book by J. Kohanoff can also be used (skip sections 5.3, 5.5, 5.6, 8.38.6, 9.4, 9.5, 10.2, 10.3, and the whole Chap.12). One of the latter references is a must if you have not yet used another electronic structure code or a Quantum Chemistry package.
After the tutorial, you might find it useful to learn about the test cases contained in the subdirectories of ~abinit/tests/, e.g. the directories fast, v1, v2, … , that provide many example input files. You should have a look at the README files of these directories.
Basic tutorials & ABINIT_build¶
The basic tutorials 14 present the basic concepts, and form a global entity: you should not skip any of these.

The basic tutorial 1 deals with the H2 molecule: get the total energy, the electronic energies, the charge density, the bond length, the atomisation energy

The basic tutorial 2 deals again with the H2 molecule: convergence studies, LDA versus GGA

The basic tutorial 3 deals with crystalline silicon (an insulator): the definition of a kpoint grid, the smearing of the cutoff energy, the computation of a band structure, and again, convergence studies …

The basic tutorial 4 deals with crystalline aluminum (a metal), and its surface: occupation numbers, smearing the FermiDirac distribution, the surface energy, and again, convergence studies …

The ABINIT_build tutorial explains how to compile ABINIT from source including the external libraries. More advanced topics such as using modules in supercomputing centers, compiling and linking with the intel compilers and the MKL library as well as OpenMP threads are also discussed.
Intermediate level tutorials¶
Tutorials in this group are prerequisite for several other tutorials. Whether it is worth to read them depend on what you are trying to compute with ABINIT.

The tutorial on the use of PAW (PAW1) presents the ProjectorAugmented Wave method, implemented in ABINIT as an alternative to normconserving pseudopotentials, with a sizeable accuracy and CPU time advantage.

The tutorial on spin in ABINIT presents the properties related to spin: spinpolarized calculations and spinorbit coupling.

The tutorial on polarization and finite electric field deals with the computation of the polarization of an insulator (e.g. ferroelectric, or dielectric material) thanks to the Berry phase approach, and also presents the computation of materials properties in the presence of a finite electric field (also thanks to the Berry phase approach).

An introduction on parallelism in ABINIT should be read before going to the next tutorials about parallelism. One simple example of parallelism in ABINIT will be shown.

The tutorial DFPT1 (RF1  response function 1) presents the basics of DFPT within ABINIT. The example given is the study of dynamical and dielectric properties of AlAs (an insulator): phonons at Gamma, dielectric constant, Born effective charges, LOTO splitting, phonons in the whole Brillouin zone. The creation of the “Derivative Data Base” (DDB) is presented.
The additional information given by tutorial DFPT1 opens the door to:
 The tutorial DFPT2 (RF2  response function 2) presents the analysis of the DDBs that have been introduced in the preceeding tutorial RF1. The computation of the interatomic forces and the computation of thermodynamical properties is an outcome of this tutorial.
Other tutorials present more specialized topics.
ABINIT postprocessors¶
Some ABINIT postprocessors have one dedicated tutorial. For some processors (ANADDB, MULTIBINIT), there are even more tutorials, presented under other themes. Alternatively, there are also specific User Guides for several postprocessors..

The tutorial on aTDEP (aTDEP1) shows how to capture anharmonicities by means of an harmonic Temperature Dependent Effective Potential (TDEP).

The tutorial on cut3d deals with the use of the CUT3D utility to analyse wavefunctions and densities.

The tutorial on the fold2bloch postprocessor deals with the use of the fold2Bloch utility to unfold band structures from supercell calculations.

The tutorial on Optic, the utility that allows one to obtain the frequencydependent linear optical dielectric function and the frequency dependent second order nonlinear optical susceptibility, in the simple “SumOverState” approximation. Prerequisite: DFPT1.

The tutorial on Wannier90 deals with the Wannier90 library to obtain Maximally Localized Wannier Functions.

The tutorial on Z2Pack shows how to use the Z2Pack application with an interface to ABINIT, to compute the Z2 topological invariant and find topologically nontrivial insulators.
DFT beyond basics¶
** Prerequisite: PAW1.**

The tutorial on the properties at nucleus shows how to compute the electric field gradient and isomer shift (at the nucleus position).

The tutorial on DFT+U shows how to perform a DFT+U calculation using ABINIT, and will lead to compute the projected DOS of NiO.

The tutorial U_calc_cRPA shows how to determine the U value for DFT+U with the constrained Random Phase Approximation (cRPA) using projected Wannier orbitals. Prerequisite: DFT+U. Require at least 8 cores.

The tutorial LRUJ shows how to determine the U value for DFT+U with the linear response method. Prerequisite: DFT+U.

The tutorial PAW2 presents the generation of atomic data for use with the PAW method.

The tutorial PAW3 demonstrates how to test a generated PAW dataset using ABINIT, against the ELK allelectron code, for diamond and magnesium. Prerequisite: PAW2.

The tutorial on electronpositron annihilation shows how to perform TwoComponent DensityFunctional Theory (TCDFT) calculations in the PAW framework to obtain the positron lifetime in the perfect material, the lifetime of a positron localized in a vacancy, the electronpositron momentum distribution wavefunctions and densities.
ManyBody Theory & excitations¶
This group of three tutorials on ManyBody Perturbation Theory (GW approximation, BetheSalpeter equation) is to be done sequentially:

The first tutorial on GW (GW1) deals with the computation of the quasiparticle band gap of Silicon (semiconductor), in the GW approximation (much better than the KohnSham LDA band structure), with a plasmonpole model.

The second tutorial on GW (GW2) deals with the computation of the quasiparticle band structure of Aluminum, in the GW approximation (so, much better than the KohnSham LDA band structure) without using the plasmonpole model.

The tutorial on the BetheSalpeter Equation (BSE) deals with the computation of the macroscopic dielectric function of Silicon within the BetheSalpeter equation.
The two following tutorials do not rely on ManyBody Perturbation Theory

The tutorial on DFT+DMFT shows how to perform a DFT+DMFT calculation on SrVO3 using projected Wannier functions. Prerequisite: DFT+U.

The tutorial on TDDFT deals with the computation of the excitation spectrum of finite systems, thanks to the TimeDependent Density Functional Theory approach, in the Casida formalism.
Advanced tutorials on DFPT & electronphonon interaction.¶
Prerequisite DFPT1 for all tutorials in this section. Also DFPT2 for all electronphonon tutorials.
Densityfunctional perturbation theory gives access to many properties of materials (phonons, dielectric constant, electronphonon interaction, elastic response, Raman coefficients, piezoelectricity …)

The tutorial on the elastic properties presents the computation with respect to the strain perturbation and its responses: elastic constants, piezoelectricity.

The tutorial on static nonlinear properties presents the computation of responses beyond the linear order, within DensityFunctional Perturbation Theory (beyond the simple SumOverState approximation): Raman scattering efficiencies (nonresonant case), nonlinear electronic susceptibility, electrooptic effect. Comparison with the finite field technique (combining DFPT calculations with finite difference calculations), is also provided.

The tutorial on building Lattice wannier function presents how to use anaddb to build the lattice Wannier functions (LWF).
Electronphonon interaction has been the subject of major efforts in the last years. Three tutorials are already available to present the new implementations.

The introductive tutorial on the electronphonon interaction presents the electronphonon driver integrated with the ABINIT executable, discuss important technical details related to the implementation and the associated input variables. The drawbacks/advantages with respect to the implementation available in ANADDB are also discussed.

The tutorial on mobility calculations explains how to compute phononlimited carrier mobilities in semiconductors within the relaxation time approximation (RTA)

The tutorial on zeropoint renormalization and temperaturedependence of electronic structure explains how to obtain the electron selfenergy due to phonons, compute the zeropoint renormalization (ZPR) of the band gap as well as temperaturedependent band gaps (or the whole electronic structure).
Two legacy tutorials on electronphonon interaction are still present. The implementations are still available at time of writing, but have been superseded by the new implementations, described in the abovementioned tutorials.

The legacy tutorial on the electronphonon interaction presents the use of the utility MRGKK and ANADDB to examine the electronphonon interaction and the subsequent calculation of superconductivity temperature (for bulk systems).

The legacy tutorial on temperature dependence of the electronic structure presents the computation of the temperature dependence of the electronic structure, the zeropoint motion effect, the lifetime/broadening of eigenenergies.
MULTIBINIT tutorials¶
Prerequisite DFPT1 and DFPT2 for all tutorials in this section.

The introductory tutorial on MULTIBINIT presents the MULTIBINIT project

The first tutorial on MULTIBINIT presents the basic use of the MULTIBINIT application, how to build a harmonic model by using a secondprinciples approach for lattice dynamics simulations based on atomic potentials fitted on firstprinciples calculations. Prerequisite polarization.

The second tutorial on MULTIBINIT presents how to build a spin model and run spin dynamics in MULTIBINIT. Prerequisite spin.

The third tutorial on MULTIBINIT presents how to run a lattice Wannier function (LWF) dynamics in MULTIBINIT. Prerequisite lattice_wannier.
Advanced tutorials on parallelism¶
Prerequisite parallelism for all tutorials in this section.
For each of these tutorials, familiarization with the corresponding tutorial for the sequential calculation is mandatory, if it exists.

Parallelism for groundstate calculations, based on band and plane waves distribution  paral_bandpw presents the combined kpoint (K), planewave (G), band (B), spin/spinor parallelism of ABINIT (so, the “KGB” parallelism), for the computation of total energy, density, and ground state properties

Parallelism for groundstate calculations, with wavelets presents the parallelism of ABINIT, when wavelets are used as a basis function instead of planewaves, for the computation of total energy, density, and ground state properties

Parallelism based on “images”, e.g. for the determination of transitions paths (NEB or string method), or for PIMD, that can be activated alone, or on top of other parallelisms, e.g. the “KGB” parallelism for force calculations.

Parallelism of DFPT calculations you need to be familiarized with the calculation of response properties within ABINIT, see the tutorial DFPT 1 (RF1)

Parallelism of ManyBody Perturbation calculations (GW)  paral_MBPT allows to speed up the calculation of accurate electronic structures (quasiparticle band structure, including manybody effects).
Note
Note that not all features of ABINIT are covered by these tutorials. For a complete feature list, please see the Topics page. For examples on how to use these features, please see the ~abinit/tests/* directories and their accompanying README files.