  We present a first-principles calculation of the electronic conduction
properties of single-row sodium nanowires suspended between semi-infinite
electrodes. The conductance of the nanowire is ~1 G0 (=2e^2/h) and oscillates
with a two-atom period as the number of the atoms within the nanowire varies.
Moreover, we observed bunches of high electron density with a two atom-lengths
in the channel density distribution. The relation between the period of the
conductance oscillation and the length of bunches are examined by using
simplified models and is found to be largely affected by the characteristics of
the infinite wire.
