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Welcome to the ABINIT Tutorial

ABINIT: the tutorial

The lessons of this tutorial are aimed at teaching the use of ABINIT, in the UNIX/Linux OS and its variants (OSF, HP-UX, AIX ...). They might be used for other operating systems, but the commands have to be adapted.

Note that they can be accessed from the ABINIT web site as well as from your local ~abinit/doc/tutorial/welcome.html file. The latter solution is of course preferable, as the response time will not depend on the network traffic.

At present, more than thirty lessons are available. Each of them is at most two hours of student work. Lessons 1-4 cover the basics, other lectures are more specialized.

Copyright (C) 2000-2015 ABINIT group (XG,RC)
This file is distributed under the terms of the GNU General Public License, see ~abinit/COPYING or .
For the initials of contributors, see ~abinit/doc/developers/contributors.txt .

Before following the tutorials, you should have read the "new user's guide", as well as the pages 1045-1058 of the paper "Iterative minimization techniques for ab initio total-energy calculations: molecular dynamics and conjugate gradients", by M.C. Payne, M.P. Teter, D.C. Allan, T.A. Arias and J.D. Joannopoulos, Rev. Mod. Phys. 64, 1045 (1992) or, if you have more time, you should browse through the Chaps. 1 to 13 , and appendices L and M of the book Electronic Structure. Basic Theory and Practical Methods. R. M. Martin. Cambridge University Press (2004) ISBN 0 521 78285 6. The latter reference 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, ... v6, that provide many example input files. You should have a look at the README files of these directories.

Additional information can be found in the ~abinit/doc directory, including the description of the ABINIT project, guide lines for developpers, more on the use of the code (tuning) ...

Some lessons depends on other lessons. The following schema should help you to understand these dependencies. In blue, one has the basic lessons. The blocks in red represents additional lessons related to ground-state features of ABINIT. Response-function features of ABINIT are explained in the lessons in the green blocks. Finally, the Many-Body Perturbation Theory capabilities are demonstrated in the lessons belonging to the violet blocks. The right-hand side blocks gather the lessons related to the parallelism inside ABINIT.

Schema 1

Brief description of each lesson's content

The lessons 1-4 present the basic concepts, and form a global entity: you should not skip any of these.

  • The lesson 1 deals with the H2 molecule : get the total energy, the electronic energies, the charge density, the bond length, the atomisation energy
  • The lesson 2 deals again with the H2 molecule: convergence studies, LDA versus GGA
  • The lesson 3 deals with crystalline silicon (an insulator): the definition of a k-point grid, the smearing of the cut-off energy, the computation of a band structure, and again, convergence studies ...
  • The lesson 4 deals with crystalline aluminum (a metal), and its surface: occupation numbers, smearing the Fermi-Dirac distribution, the surface energy, and again, convergence studies ...

Other lessons present more specialized topics.

There is a group of lessons that can be started without any other prerequisite than the lessons 1 to 4, and that you can do in any order (there are some exceptions, though):

There is an additional group of lessons on response functions (phonons, optics, dielectric constant, electron-phonon interaction, elastic response, non-linear optics, Raman coefficients, piezoelectricity ...), for which some common additional information are needed:

  • The lesson Response-Function 1 (RF1) presents the basics of response-functions 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, LO-TO splitting, phonons in the whole Brillouin zone. The creation of the "Derivative Data Base" (DDB) is presented.
  • The lesson Response-Function 2 (RF2) presents the analysis of the DDBs that have been introduced in the preceeding lesson RF1. The computation of the interatomic forces and the computation of thermodynamical properties is an outcome of this lesson.
  • The additional information given by lesson RF1 opens the door to The lesson on Optic, the utility that allows to obtain the frequency dependent linear optical dielectric function and the frequency dependent second order nonlinear optical susceptibility, in the simple "Sum-Over-State" approximation.
  • The additional information given by lesson RF1 and RF2 opens the door to a group of lessons that can be followed independently of each other: The lesson on the electron-phonon interaction presents the use of the utility MRGKK and ANADDB to examine the electron-phonon interaction and the subsequent calculation of superconductivity temperature (for bulk systems).
  • The lesson on the elastic properties presents the computation with respect to the strain perturbation and its responses: elastic constants, piezoelectricity.
  • The lesson on static non-linear properties presents the computation of responses beyond the linear order, within Density-Functional Perturbation Theory (beyond the simple Sum-Over-State approximation): Raman scattering efficiencies (non-resonant case), non-linear electronic susceptibility, electro-optic effect. Comparison with the finite field technique (combining the computation of linear response functions with finite difference calculations), is also provided.

An additional lesson has been developed outside the standard structure of the ABINIT tutorial, in the experimental Wiki of ABINIT, The lesson on temperature-dependence of the electronic structure.

There is another additional group of lessons on many-body perturbation theory (GW approximation, Bethe-Salpeter equation), to be done sequentially):

  • The first lesson on GW deals with the computation of the quasi-particle band gap of Silicon (semiconductor), in the GW approximation (much better than the Kohn-Sham LDA band structure), with a plasmon-pole model.
  • The second lesson on GW deals with the computation of the quasi-particule band structure of Aluminum, in the GW approximation (so, much better than the Kohn-Sham LDA band structure) without using the plasmon-pole model.
  • The lesson on BSE deals with the computation of the macroscopic dielectric function of Silicon within the Bethe-Salpeter equation.

Concerning parallelism, there is another set of specialized lessons. For each of these lessons, you are suposed to be familiarized with the corresponding tutorial for the sequential calculation.

The following topics should be covered later:

  • the choice of pseudopotentials

NOTE that not all features of ABINIT are covered by these tutorials. For a complete feature list, please see the ~abinit/doc/features/ directory. For examples on how to use these features, please see the ~abinit/tests/* directories and their accompanying README files.