cooling cycles (circles). []{data-label="figure2"}](fig2){width="7cm"}

MC simulation were carried out on rectangular lattice of linear size $L_x, L_y$ along x, y direction, respectively with periodic boundary conditions (PBC). To check the role of PBC additional simulations were performed with boundary atoms fixed at positions of the flat bcc(111) surface. The results are consistent with those obtained for calculation with PBC.

First, we investigate properties of the system with coupling constant $K=-1.25$ during warming up process. At each temperature $T_i=T_{i-1} + \Delta T$ system spends the same annealing time $\tau$ measured in Monte Carlo steps per site. The ideal bcc(111) surface is used as a starting configuration at $T_0$. We also investigate properties of the system during cooling down the sample. Results of simulations for the following parameters: $Lx=192$, $Ly=336$, $\Delta T=0.03$ and $\tau= 
3\times 10^5$ are presented in Fig. \[figure2\]-Fig.  \[figure5\]. Let us notice that these sizes of the lattice correspond to the area of $426\mbox{\AA} \times 431\mbox{\AA}$ on the bcc(111) surface with the lattice constant $a=3.14\mbox{\AA}$.

The surface formation energy decreases as temperature is elevated (see Fig. \[figure2\]) what indicates reconstruction of the surface. At $T\approx 0.4$ very small 3-sided {211} pyramids are formed on the surface and further warming 