### bkpts

The bkpts-file contains information on the nearest neighbors of the k-points. Here is an example:

   8
1     2      0   0   0
1     3      0   0   0
1     5      0   0   0
1     8      0   0   0
1     2      0   0  -1
1     3      0  -1   0
1     5     -1   0   0
1     8     -1  -1  -1
2     1      0   0   0
2     4      0   0   0
2     6      0   0   0
2     1      0   0   1
2     7      0   0   1
2     4      0  -1   0
2     6     -1   0   0
2     7     -1  -1   0
3     1      0   0   0
3     4      0   0   0
3     7      0   0   0
3     1      0   1   0
3     6      0   1   0
3     4      0   0  -1
3     7     -1   0   0
3     6     -1   0  -1
4     2      0   0   0
4     3      0   0   0
4     8      0   0   0
4     2      0   1   0
4     3      0   0   1
4     5     -1   0   0
4     8     -1   0   0
4     5      0   1   1
5     1      0   0   0
5     6      0   0   0
5     7      0   0   0
5     1      1   0   0
5     4      1   0   0
5     6      0   0  -1
5     7      0  -1   0
5     4      0  -1  -1
6     2      0   0   0
6     5      0   0   0
6     8      0   0   0
6     2      1   0   0
6     5      0   0   1
6     3      0  -1   0
6     8      0  -1   0
6     3      1   0   1
7     3      0   0   0
7     5      0   0   0
7     8      0   0   0
7     3      1   0   0
7     5      0   1   0
7     2      0   0  -1
7     8      0   0  -1
7     2      1   1   0
8     1      0   0   0
8     4      0   0   0
8     6      0   0   0
8     7      0   0   0
8     1      1   1   1
8     4      1   0   0
8     6      0   1   0
8     7      0   0   1


At the top, the number of nearest neighbors of each k-point is given. Here, it is 8, which is the number of nearest neighbors in the bcc-lattice. The rest of the file is composed of 5 columns. The first column gives the index of a k-point. The second column gives the index of a nearest neighbor of that k-point, if the nearest neighbor lies in the first Brillouin zone. If a nearest neighbor is not located in the first Brillouin zone, then a translation by a reciprocal lattice vector is applied to it to move it into the first Brillouin zone. The index of the nearest neighbor refers then to a k-point in the first Brillouin zone and the last three columns specify the reciprocal lattice vector needed for the translation.