  Accuracy of the Kramers approximate formula for the thermal decay rate of the
metastable state is studied for the two-dimensional potential pocket. This is
done by the comparison with the quasistationary rate resulting from the
dynamical modeling. It is shown that the Kramers rate is in agreement with the
quasistationary rate within the statistical errors provided the absorptive
border is far enough from the potential ridge restricting the metastable state.
As the absorptive border (or its part) gets closer to the ridge the Kramers
formula underestimate the quasistationary rate. The difference reaches
approximately the factor of 2 when the absorptive border coincides with the
ridge.
