Element: structure
This element contains all structural information, such as unit-cell parameters as well as type and position of each atom. The presence of the subelement species is necessary unless one wants to perform an empty-lattice calculation. The attribute speciespath must be specified.
contains: | crystal (required) species (optional) |
XPath: | /input/structure |
This element allows for specification of the following attributes: speciespath (required), autormt, epslat, molecule, primcell, rmtapm, tshift, vacuum
Attribute: autormt
If "true", the muffin-tin radius of each species is automatically set according to the variables specified by the attribute rmtapm.
Type: | boolean |
Default: | "false" |
Use: | optional |
XPath: | /input/structure/@autormt |
Attribute: epslat
This attribute defines the accuracy up to which two vectors can be considered numerically identical. Vectors with lengths less than this are considered zero.
Type: | fortrandouble |
Default: | "1.0d-6" |
Use: | optional |
Unit: | Bohr |
XPath: | /input/structure/@epslat |
Attribute: molecule
If "true", a calculation for an isolated molecule is performed. In this case, the atomic positions specified by the atom subelement of the species element must be given in cartesian coordinates. The lattice vectors are set up automatically as
(1)with
(2)where ${a}_i^{(\alpha)}$ is the catesian component of the atom labeled by $\alpha$ in the $i$-th direction specified by the unit vector $\hat{\bf e}^{(i)}$. Furthermore, $d_{\rm vac}$ represents the size of the vacuum around the molecule as defined by the attribute vacuum.
Type: | boolean |
Default: | "false" |
Use: | optional |
XPath: | /input/structure/@molecule |
Attribute: primcell
If "true", the primitive unit cell is determined automatically from the conventional cell defined by the basis vectors given by the basevect elements. The primitive unit cell is determined by searching for lattice vectors among all vectors connecting atomic sites and choosing the three shortest ones which produce a unit cell with non-zero volume.
Type: | boolean |
Default: | "false" |
Use: | optional |
XPath: | /input/structure/@primcell |
Attribute: rmtapm
This attribute assigns the two parameters governing the automatic generation of the muffin-tin radii. When the attribute autormt is set to "true", the muffin-tin radii are determined according to the following expression
(3)where $Z_i$ is the atomic number of the $i$ th species, $\zeta$ is stored in rmtapm(1). The distance between the muffin-tin speheres is determined by the value of rmtapm(2): When rmtapm(2)=1, the closest muffin-tin spheres will touch each other.
Type: | vect2d |
Default: | "0.25d0 0.95d0" |
Use: | optional |
XPath: | /input/structure/@rmtapm |
Attribute: speciespath
The path to the directory containing the species files. Alternatively, it can be defined as an HTTP URL, in this case the wget utility must be installed.
Type: | anyURI |
Use: | required |
XPath: | /input/structure/@speciespath |
Attribute: tshift
If "true", the crystal is shifted such that the atom closest to the origin is exactly at the origin.
Type: | boolean |
Default: | "true" |
Use: | optional |
XPath: | /input/structure/@tshift |
Attribute: vacuum
Determines the size of the vacuum around the molecule, see the molecule attribute.
Type: | fortrandouble |
Default: | "10.0d0" |
Use: | optional |
Unit: | Bohr |
XPath: | /input/structure/@vacuum |
Element: crystal
Defines the unit cell of the crystal via the 3 basis vectors.
contains: | basevect (required) |
XPath: | /input/structure/crystal |
This element allows for specification of the following attributes: scale, stretch
Attribute: scale
Scales all the lattice vectors by the same factor. This is useful for varying the volume.
Type: | fortrandouble |
Default: | "1.0d0" |
Use: | optional |
Unit: | 1 |
XPath: | /input/structure/crystal/@scale |
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: | /input/structure/crystal/@stretch |
Element: basevect
Defines one basis vector in Cartesian coordinates.
Type: | vect3d |
Unit: | Bohr |
XPath: | /input/structure/crystal/basevect |
Element: species
Defines the atomic species, i.e., the chemical element. Aatomic coordinates and, optionally, quantities relevant for magnetic calculations are defined in the subelement(s) atom.
contains: | atom (required) LDAplusU (optional) |
XPath: | /input/structure/species |
This element allows for specification of the following attributes: speciesfile (required), rmt
Attribute: rmt
Defines the muffin-tin radius. This optional parameter allows to override the value either specified in the species file or generated by automatic determination. The muffin-tin radius defines the region around the atomic nucleus where the wave function is expanded in terms of atomic-like functions. In contrast, the interstitial region, i.e., the region not belonging to any muffin-tin sphere, is described by planewaves.
Type: | fortrandouble |
Default: | "-1.0d0" |
Use: | optional |
Unit: | Bohr |
XPath: | /input/structure/species/@rmt |
Attribute: speciesfile
Defines the file that contains the species definition. It is looked up in the species directory specified by speciespath. By default, the name of the file is element.xml, e.g., Ag.xml.
Type: | anyURI |
Use: | required |
XPath: | /input/structure/species/@speciesfile |
Element: atom
Defines the position and other attributes of one atom in the unit cell.
Type: | no content |
XPath: | /input/structure/species/atom |
This element allows for specification of the following attributes: coord (required), bfcmt, mommtfix
Attribute: bfcmt
Muffin-tin external magnetic field in Cartesian coordinates.
Type: | vect3d |
Default: | "0.0d0 0.0d0 0.0d0" |
Use: | optional |
XPath: | /input/structure/species/atom/@bfcmt |
Attribute: coord
Atom position in lattice coordinates.
Type: | vect3d |
Use: | required |
Unit: | lattice coordinates |
XPath: | /input/structure/species/atom/@coord |
Attribute: mommtfix
The desired muffin-tin moment for a Fixed Spin Moment (FSM) calculation.
Type: | vect3d |
Default: | "0.0d0 0.0d0 0.0d0" |
Use: | optional |
XPath: | /input/structure/species/atom/@mommtfix |
Element: LDAplusU
The LADplusU element is used to specify the J, U, and l parameters of an atomic species. To switch on the LDAplusU feature one needs to set the ldapu attribute of the groundstate element.
Type: | no content |
XPath: | /input/structure/species/LDAplusU |
This element allows for specification of the following attributes: J, U, l
Attribute: J
Type: | fortrandouble |
Default: | "0.0d0" |
Use: | optional |
XPath: | /input/structure/species/LDAplusU/@J |
Attribute: U
Type: | fortrandouble |
Default: | "0.0d0" |
Use: | optional |
XPath: | /input/structure/species/LDAplusU/@U |
Attribute: l
Type: | integer |
Default: | "-1" |
Use: | optional |
XPath: | /input/structure/species/LDAplusU/@l |
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.