I'm simulating a nano particle and wish to calculate the activation energy of the reaction where an atom is displaced from one point on the lattice to a neighboring void( might be at higher energy than initial). Calculating this activation energy using energy difference will require me to calculate the complete trajectory to determine the point with highest energy, which is computationally very expensive. Is there any other tested method to find this activation energy without having to perform so many computations each time. Note: the new site is a neighbor of the old site and I expect( not assume) the atom to roll over two of its adjacent atoms to reach this new site. Also all the atoms are identical.