I have constructed a atomic asperity junction between Al and Fe. However, a repulsive force occurs before the snap to contact happen. This is quite different with the phenomena from some relevant literature,in which there is no repulsive forces before the attraction happens. Moreover, there has been very little research on the nanocontact between BCC Fe and FCC Al both experimentally and numerically.

I would like to ask: is this consistent with the real physical phenomena?