This keyword determines the number of bands at each k-point when performing a band structure calculation.
There are three ways in which you can specify the number of bands at each k-point:
It is not possible to have both the BS_NBANDS keyword and either the BS_NEXTRA_BANDS or BS_PERC_EXTRA_BANDS keywords present in the same input file.
NBANDS + 5√NBANDS
BS_NBANDS : 64
CASTEP keyword glossary
CASTEP parameters keywords