# 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
%endblock

# 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