The Free Energy Barrier of Molecular Motions in Bistable [2]Rotaxane Molecular Electronic Devices : Supplementary Materials Hyungjun Kim, 1 William A. Goddard III, 1,* Seung Soon Jang, 2, * William R. Dichtel, 3,4 James R. Heath, 3 and J. Fraser Stoddart 5 1 Materials and Process Simulation Center (MC 139-74) California Institute of Technology, Pasadena, CA 91125 2 School of Materials Science and Engineering Georgia Institute of Technology, Atlanta, GA 30332-0245 3 Division of Chemistry and Chemical Engineering (MC 127-72), California Institute of Technology, Pasadena, CA, 91125 4 Department of Chemistry and Biochemistry University of California, Los Angeles, California, 90095-1569 5 Department of Chemistry, Northwestern University, Evanston, IL 60208 * To whom correspondence should be addressed. E-mail: wag@wag.caltech.edu and SeungSoon.Jang@mse.gatech.edu