In this format an explicit listing of all coordinates and of the connection tables for the tetrahedra -- if one wants to use the tetrahedron integration methods -- is supplied (the latter part can be omitted for finite temperature-smearing methods, see section 9.4). The most general format is:

Example file 4 Cartesian 0.0 0.0 0.0 1. 0.0 0.0 0.5 1. 0.0 0.5 0.5 2. 0.5 0.5 0.5 4. Tetrahedra 1 0.183333333333333 6 1 2 3 4The first line is treated as a comment line. In the second line you must provide the number of k-points and in the third line you have to specify whether the coordinates are given in cartesian or reciprocal coordinates. Only the first character of the third

where are the three reciprocal basis vectors, and are the supplied values. In the cartesian input format the k-points are given by

The following example illustrates how to specify the kpoints. The unit cell of the fcc lattice is spanned by the following basis vectors:

the reciprocal lattice is defined as :

The following input is required in order to specify the high symmetry k-points.

Point Cartesian coordinates Reciprocal coordinates (units of 2pi/a) (units of b1,b2,b3) ------------------------------------------------------ G ( 0 0 0 ) ( 0 0 0 ) X ( 0 0 1 ) ( 1/2 1/2 0 ) W ( 1/2 0 1 ) ( 1/2 3/4 1/4 ) K ( 3/4 3/4 0 ) ( 3/8 3/8 3/4 ) L ( 1/2 1/2 1/2 ) ( 1/2 1/2 1/2 )

If the tetrahedron method is not used the KPOINTS file may end after the
list of coordinates.
The tetrahedron method requires an additional connection list for the
tetrahedra:
In this case, the next line must
start with 'T' or 't' signaling that this connection list is supplied.
On the next line after this 'control line' one must enter the number
of tetrahedra and the volume weight for a single tetrahedron (all tetrahedra must have
the same volume). The volume weight is simply the ratio between the tetrahedron
volume and the volume of the (total) Brillouin zone.
Then a list with the (symmetry degeneration)
weight and the four corner points of each tetrahedron follows
(four integers which represent
the indices to the points in the k-point list given above, 1 corresponds to the
first entry in the list).
*Warning*: In contrast to the weighting factors
for each k-point you must provide the *correct* 'volume weight' and (symmetry
degeneration) weight for each tetrahedron - no internal renormalization
will be done by VASP!

This method is normally used if one has only a few number of k-points or if one wants to select some specific k-points which do not form a regular mesh (e.g. for calculating the bandstructure along some special lines within the Brillouin zone, section 11.3). Tetrahedron connection tables will rarely be given 'by hand'. Nevertheless this method for providing all k-point coordinates and weights (and possibly the connection lists) as also important if the mesh contains a very large number of k-points: VASP (or an external tool called 'k-points') can calculate regular k-meshes automatically (see next section) generating an output file IBZKPT which has a valid KPOINTS-format. For very large meshes it takes a lot of CPU-time to generate the mesh. Therefore, if you want to use the same k-mesh very frequently do the automatic generation only once and copy the file IBZKPT to the file KPOINTS. In subsequent runs, VASP can avoid a new generation by reading the explicit list given on this file.

Mon Mar 29 10:38:29 MEST 1999