Spacegroup Input Reference

Element: symmetries

The symmetries file format used by the spacegroup tool to generate structures and supercells as defined by lattice from the knowledge of Wyckoff positions and the space group. The space group is specified by the attribute HermannMauguinSymbol. The root element is symmetries.

contains: title (required)
lattice (required)
WyckoffPositions (optional)
XPath: ./symmetries

This element allows for specification of the following attributes: HermannMauguinSymbol (required)

Attribute: HermannMauguinSymbol

The Herman Mauguin symbol specifies the spacegroup of the structure. The table of all the symbols lists all possible inputs.

Type: string
Use: required
XPath: ./symmetries/@HermannMauguinSymbol

Element: title

Type: string
XPath: ./symmetries/title

Element: lattice

The lattice element defines lattice from a,b,c, and angles.

Type: no content
XPath: ./symmetries/lattice

This element allows for specification of the following attributes: a (required), ab (required), ac (required), b (required), bc (required), c (required), epslat, ncell, primcell, scale, speciespath, stretch

Attribute: a

Type: fortrandouble
Use: required
Unit: Bohr
XPath: ./symmetries/lattice/@a


Attribute: ab

Angle between lattice vector a and b in degrees.

Type: fortrandouble
Use: required
Unit: Degree
XPath: ./symmetries/lattice/@ab


Attribute: ac

Angle between lattice vector a and c in degrees.

Type: fortrandouble
Use: required
Unit: Degree
XPath: ./symmetries/lattice/@ac


Attribute: b

Type: fortrandouble
Use: required
Unit: Bohr
XPath: ./symmetries/lattice/@b


Attribute: bc

Angle between lattice vector b and c in degrees.

Type: fortrandouble
Use: required
Unit: Degree
XPath: ./symmetries/lattice/@bc


Attribute: c

Type: fortrandouble
Use: required
Unit: Bohr
XPath: ./symmetries/lattice/@c


Attribute: epslat

Type: fortrandouble
Default: "1.0d-6"
Use: optional
XPath: ./symmetries/lattice/@epslat


Attribute: ncell

Number of repeated cells in each direction.

Type: integertriple
Default: "1 1 1"
Use: optional
XPath: ./symmetries/lattice/@ncell


Attribute: primcell

Type: boolean
Default: "false"
Use: optional
XPath: ./symmetries/lattice/@primcell


Attribute: scale

Scales all the lattice vectors by the same factor. This is useful for varying the volume.

Type: fortrandouble
Default: "1"
Use: optional
XPath: ./symmetries/lattice/@scale


Attribute: speciespath

Type: string
Default: "http://xml.exciting-code.org/species/"
Use: optional
XPath: ./symmetries/lattice/@speciespath


Attribute: stretch

Allows for an individual scaling of each lattice vector separately. "1 1 1" means no scaling.

Type: vect3d
Default: "1.0d0 1.0d0 1.0d0 "
Use: optional
XPath: ./symmetries/lattice/@stretch

Element: WyckoffPositions

contains: wspecies (optional)
XPath: ./symmetries/WyckoffPositions

Element: wspecies

contains: wpos (optional)
XPath: ./symmetries/WyckoffPositions/wspecies

This element allows for specification of the following attributes: speciesfile

Attribute: speciesfile

Type: string
Use: optional
XPath: ./symmetries/WyckoffPositions/wspecies/@speciesfile

Element: wpos

Type: no content
XPath: ./symmetries/WyckoffPositions/wspecies/wpos

This element allows for specification of the following attributes: coord

Attribute: coord

Type: vect3d
Use: optional
XPath: ./symmetries/WyckoffPositions/wspecies/wpos/@coord

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.

Type fortrandouble

The type fortrandouble allows to use the letters "eEdDqQ" for exponent operators. This alters in what precision the number is parsed.

Type booleanlist

List of space separated booleans.

Type booleantriple

Space separated list of three booleans.

Example: "true false true"

Type vector

A vector is a space separated list of floating point numbers.

Example: "1.3 2.3e4 3 90"

Type integerlist

List of space separated integers.

Type vect3d

Three dimensional vector as three space separated floating point numbers.

Type vect2d

Two dimensional vector as two space separated floating point numbers.

Type integertriple

Space separated list of three integers.

Example: "1 2 3"

Type integerquadrupel

Space separated list of three integers.

Example: "1 2 3 4"

Type integerpair

Space separated list of two integers

Example: "1 2"

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