  Recently Y. N. showed that the nonequilibrium critical relaxation of the 2D
Ising model from the perfectly-ordered state in the Wolff algorithm is
described by the stretched-exponential decay, and found a universal scaling
scheme to connect nonequilibrium and equilibrium behaviors. In the present
study we extend these findings to vector spin models, and the 3D Heisenberg
model could be a typical example. In order to evaluate the critical temperature
and critical exponents precisely with the above scaling scheme, we calculate
the nonequilibrium ordering from the perfectly-disordered state in the
Swendsen-Wamg algorithm, and find that the critical ordering process is
described by the stretched-exponential growth with the comparable exponent to
that of the 3D XY model. The critical exponents evaluated in the present study
are consistent with those in previous studies.
