  Ab initio molecular dynamics simulation is used to investigate the structure
and dynamics of liquid Se at temperatures of 870 and 1370~K. The calculated
static structure factor is in excellent agreement with experimental data. The
calculated radial distribution function gives a mean coordination number close
to 2, but we find a significant fraction of one-fold and three-fold atoms,
particularly at 1370~K, so that the chain structure is considerably disrupted.
The self-diffusion coefficient has values ($\sim 1 \times 10^{-8}$~m~s$^{-1}$)
typical of liquid metals.
