castep error

I'm a beginner and I failed when performing geometric optimization on the crystal model (including the model and its cross-sections). This is the failure message. I hope the experienced teachers can help me interpret why it failed.

Error geom_precon_exp_get_r_NN: increased r_cut  to twice system extent without finding neighbours  for all atoms. This can happen if your system is too small;  try setting r_cut manually
Current trace stack:
geom_precon_exp_initialize
geom_precon_initialize
geom_BFGS
geometry_optimise
castep
[mpiexec@DESKTOP-MBLM11M] ..\\hydra\\utils\\sock\\sock.c (420): write error (Unknown error)
[mpiexec@DESKTOP-MBLM11M] ..\\hydra\\utils\\launch\\launch.c (121): shutdown failed, sock 612, error 10093