  The thermal boundary resistance (Kapitza resistance) of (001) twist grain
boundaries in silicon nanowires depends on the mismatch angle. This dependence
is systematically investigated by means of nonequilibrium molecular dynamics
simulations. Grain boundary systems with and without coincidence site lattice
are compared. The Kapitza resistance increases with twist angle up to 40{\deg}.
For larger angles, it varies only little around 1.56 $\pm$ 0.05 K m^2/GW,
except for a drop by 30% near the 90{\deg} {\Sigma} 1 grain boundary. Finite
size effects due to the fixed outer boundary conditions of the nanowire are
negligible for diameters larger than 25 nm.
