1. Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
2. Department
of Physics, UC Berkeley, Berkeley, California 96720, United States
3. Department
of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
4. Materials
Theory, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich, Switzerland