Our blog posts (and emails to family and friends) have been more infrequent lately; in part due to work as well as taking an amazing tour in the north of Israel this past weekend (more on that in a future post).  For those of you who might be interested in the work – what follows is a brief description of why we are in Israel.

I’m interested in applying accurate quantum mechanical techniques to the characterization of molecules in alternative sources of energy such as oil sand and oil shale.  I’m in Israel, in Sason Shaik’s lab, to better learn a technique called Valence Bond Theory. After spending the first few weeks reading the literature (and keeping up with the work my research students are doing in Richmond!), I’ve decided to use VBT to characterize the bonding in the benzyne series:

The first step is to use Rumer’s Rules and the Weyl formula to figure out how many possible spin-paired structures (basis functions) are possible, including all covalent and ionic structures.  There are a lot!  If we focus just on the pi and sigma radical electrons/orbitals (8 electrons distributed in 8 orbitals) – there are 14 covalent structures and 1750 ionic structures (I’m going to try to write a mathematica script to auto-generate the ionic structures!)  These structures are then used in a variational way, minimizing the energy by adjusting the weights of each structure, and from this we can determine which structures are most important, thus obtaining a very detailed picture of the bonding.  I plan to construct different basis sets in order to assess, in each benzyne,  the 1.) importance of sigma and pi bonding in the ground and excited states, 2.) coupling between the sigma and pi orbitals and 3.) amount and nature of through-space and through-bond coupling.