  The temperature induced phase transition is investigated in the one-component
scalar field \phi^4 model on the lattice. Using the GPU cluster a huge amount
of Monte Carlo simulation data is collected for a wide interval of coupling
values. This gives a possibility to determine the low bound on the coupling
constant \lambda_0 when the transition happens and investigate its type. We
found that for the values of \lambda close to this bound a weak-first-order
phase transition takes place. It converts into a second order one with the
increase of \lambda. A comparison with the results obtained in analytic and
numeric calculations by other authors is given.
