dear Yajie-
I had a long drawn out mailing list question about a problem that looks exactly like yours. I had put the lattice command BEFORE the read_restart command (and no units command), so it was using lj units to define the lattice by default, as Steve has suggested. Basically, nothing should go before the read_restart, and that will avoid problems.
Erin
That looks like the output for lj units when a density of 4.39
is converted to a lattice spacing. Are you sure your script
and/or restart file are using real units and not lj at the point
in time the lattice command is executed?
Steve