For several years the Quantum Chemistry section (Kvankemiska avdelningen) at the University of Uppsala has held a mini-symposium honoring Per-Olov Löwdin, the institute’s founder. This year, being the 50th year anniversary of the institute, the symposium was a grand affair. The papers were all authored by graduates of Kvantkem, many of whom have now gone on to pursue careers well outside of quantum chemistry.

What has quantum chemistry to do with nanolithography? As we engineer truly nano-scale devices, we see more and more quantum effects. The theory developed in quantum chemistry may be brought to bear. Already, the community uses software like the Atomistix ToolKit to study nano-scale systems. I anticipate that quantum chemical methods will be used (and abused) as we engineer ever smaller systems. I will briefly summarize a few of the papers in what follows.

Several authors, led off by Prof. Yngve Öhrn, emphasized that our usual intuitive picture of more or less stationary nuclei embedded in a sea of electrons is but a theoretical fiction. If the system we study is in the ground state and there are no degeneracies among the electron states, then this so-called Born-Oppenheimer approximation is valid. Otherwise, it most certainly is not so. Prof. Öhrn has devoted many years of his career to develop computational methods to attack such systems.

Prof. Karl-Fredrik Berggren gave a fascinating talk on current flow in quantum dots. His talk was a summary of a recently published paper appearing in the New Journal of Physics. In my opinion, this is excellent physics; Prof. Berggren makes judicious approximations which tease out images by which we can comprehend complex phenomena.

I was intrigued by Prof. David Micha‘s talk on methods to compute spectra and dissipative dynamics in photoelectric materials. In this rather heavily technical overview, he also discussed photo-absorption by surface-bound clusters. The agreement between experiment and theory is not exact (due in part to experimental noise and in part to the state of the theory) but sufficient that we can probably start using computational methods to supplement experiments to improve photovoltaic performance.

In all, quantum chemistry and nano-engineering have each advanced to the point that we begin to see significant opportunities for the one to inform the other. Attending the 2010 Löwdinföreläsningar was time well spent.