Atomistic modeling for molecular electronics and spintronics: successes and challenges

Molecules offer intriguing advantages as building blocks for nanoscale electronics and spintronics: They provide reproducible well-defined arrangements of atoms in large quantities, their properties can be fine-tuned, and they can self-assemble. Studying charge and spin transport through molecular bridges also promises insight into molecules under unusual conditions. For understanding and designing experiments, atomistic modeling is essential. In this chapter, selected current challenges and recent progress in this area are summarized, concerning, e.g., the transition between tunneling and hopping mechanisms, statistics resulting from structural fluctuations, molecule–electrode and molecule–molecule interactions, spin effects, and the need for accuracy.