Introductory Tutorials

These introductory tutorials will give you an overview of how to run Conquest, the files and parameter settings required, and what output to expect.

Bulk silicon: input, output and SCF

We start with a very basic introduction to the input required for CONQUEST, the output generated, and the self-consistency (SCF) procedure; it uses the same system as the first of the examples in the manual, but provides more detail. The files are found in docs/tutorials/Introductory_1.

CONQUEST requires the following files to run:

  • The input file: Conquest_input

  • A coordinates file (name set in Conquest_input; no default)

  • Ion files (suffix .ion), which provide the pseudopotentials and pseudo-atomic orbitals (PAOs)

The input file requires the user to provide a certain amount of information. The minimal file that is provided for this tutorial gives most of these:

# Input/Output
IO.Title Bulk Si 8 atoms static
IO.Coordinates ionpos.dat

# General Parameters
General.NumberOfSpecies 1

%block ChemicalSpeciesLabel
1  28.0850   Si_SZ

# Moving Atoms
AtomMove.TypeOfRun static

# Finding the density matrix
DM.SolutionMethod diagon

# k-points
Diag.GammaCentred T
Diag.MPMesh T
Diag.MPMeshX 2
Diag.MPMeshY 2
Diag.MPMeshZ 2

The key entries are:

  • the coordinate file (IO.Coordinates);

  • the number of species (General.NumberOfSpecies);

  • the specification for the species (the block ChemicalSpeciesLabel gives the atomic mass and the ion file name for all species);

  • the type of run (AtomMove.TypeOfRun which defaults to static)

The Brillouin zone sampling must be investigated carefully, as for all periodic electronic structure calculations. The Monkhorst-Pack mesh (Diag.MPMesh) offers a convenient way to do this systematically. The job title is purely for reference. Further parameters are discussed in the next tutorial

  • The coordinate file IO.Coordinates

  • The number of species General.NumberOfSpecies

  • The ion files for the species

  • The basic input file

  • The output

  • Changing the output level and destination

  • Controlling the SCF (tolerance and iterations, options)

Bulk silicon: parameters to converge

  • The files that are needed

    • Coordinates

    • Ion files

    • Input file: Conquest_input

  • Integration grid

  • Brillouin zone sampling

  • Possibly basis set size

Bulk silicon: analysis

  • The files that are needed

    • Coordinates

    • Ion files

    • Input file: Conquest_input

  • Total DOS

  • Atom-projected DOS

  • Band structure output

  • Charge density and bands

  • Atomic charges