An elastic nanorod with rectangular cross section under longitudinal compression so that it buckles to one of two possible directions is analyzed. The resultant states can be represented by a double well potential. The aim is to calculate the rate of transition between the two buckled states. Therefore the Transition State Theory (TST) is used with methods already devised in earlier works. In these earlier approaches an approximated Hamiltonian was employed. A comparison is made between these results and a novel approach without approximation. It is found out that the approximation yields acceptable results as long as it is not used for the modes whose rate of transition diverges. (C) 2015 Elsevier B.V. All rights reserved.