Input Reference

In order to perform an exciting calculation an XML input file called input.xml must be provided.

This web page lists all elements and attributes that can be used in the input file of an exciting calculation:

• elements are defined according to the general XML conventions. Example: The element groundstate is used to set up a self-consistent calculation of the ground-state energy.
• attributes are also defined from the general XML conventions. An attribute is always connected to an element. In exciting an attribute generally specifies a parameter or a set of parameters which are connected to the corresponding element. Example: The attribute xctype of the element groundstate defines which exchange-correlation potential is used in the self-consistent calculation.

The input file of an exciting calculation has the default name input.xml. Simple examples for input files can be found in the available Tutorials. The input file input.xml must be a valid XML file and it must contain the root element input.

Unless explicitly stated otherwise, exciting uses atomic units, setting $\hbar = m_{e} = e = 1$. Relevant units are:

• Energies are given in Hartree:

$\phantom{mmm} 1\ {\rm Ha} = 2\ {\rm Ry} = 27.21138386(68)\ {\rm eV} = 4.35926\cdot 10^{-18}\ {\rm J}$

• Lengths are given in Bohr:

$\phantom{mmm} 1\ a_{\rm Bohr}\ = 0.52917720859(36)\ {\buildrel _{\circ} \over {\mathrm{A}}} \ = 0.52917720859(36) \cdot 10^{-10} \ {\rm m}$

• Magnetic fields are given in units of

$\phantom{mmm} 1\ {\rm a.u.} = \displaystyle\frac{e}{a_{\rm Bohr}^2}\ = 1717.2445320376\ {\rm Tesla}.$

Note: The electron charge is positive, so that the atomic numbers $Z$ are negative.

# Element: input

The XML element input is the root element of the exciting input file. It must contain at least the elements title, structure, and groundstate, each of them must be present only one time.

 contains: title (required) structure (required) groundstate (required) relax (optional) properties (optional) phonons (optional) xs (optional) gw (optional) keywords (optional) XPath: /input

This element allows for specification of the following attributes: sharedfs

## Attribute: sharedfs

This attributes tells if a parallel job has a shared file system. Set it to false if the processes of the job do not share a common file system. It gives exciting a chance to adapt the file IO accordingly

 Type: boolean Default: "true" Use: optional XPath: /input/@sharedfs

# Element: title

The title of the input file, e.g., "Ground-State Calculation for Aluminum".

 Type: string XPath: /input/title

# Element: keywords

The keywords tag can contain a space separated list of keywords classifying the calculation for archiving purposes. It is not used by the exciting program.

 Type: string XPath: /input/keywords

# Reused Elements

The following elements can occur more than once in the input file. There for they are listed separately.

# Data Types

The Input definition uses derived data types. These are described here.