Interview Professor Christopher J. Cramer

Professor Christopher Cramer is the Distinguished McKnight and University Teaching Professor of Chemistry, Chemical Physics, and Scientific Computation at the University of Minnesota. Cramer has been at Minnesota for his entire professional career. Before coming to Minnesota, he served in the US Army, including a tour in Iraq during Operation Desert Storm. 

This was way back before spreadsheets and so I worked on 8 x 20 paper that I self-ruled, and hand-entered data using four colors and in what must have been 4 point font. I was about ready to write up the work when 1 got orders to report to Fort Benning in a week and then go to Iraq. 1 packed up all the result in a large envelope and sent it to Don, hoping that Don would be able to follow it all. In fact, Don did write it up, and it was published while 1 was in the Gulf.  

Their early SM model was relatively crude. It had some good aspects in terms of accounting for polarization in the wavefunction, Cramer says. A key feature that nobody else had done was to include terms to account for the other components of solvation. Our model was semiempirical since we fit to experimental data, but that s what people wanted to know—they wanted the free energy of solvation. The PCM models of Tomasi and Rivail were underutilized because it was hard to make contact with particular experimental observables, but we offered that opportunity. Thus began what has been a very fruitful collaboration between Cramer and Truhlar. 

Cramer was drawn into the benzyne problem through collaborations with Professor Bob Squires. Cramer had long been interested in carbenes and related species, having worked on nitreniums with Professor Dan Falvery and trimethylenemethane with Professor Paul Dowd. In 1994, Cramer had applied DFT to XH2 species where X was B, C, and N. But the collaboration with 

Cramer considers the appreciation of how DFT performs with diradicals as the major theoretical contribution of the work on benzynes. DFT accommodated much more multireference character in singlet wavefunctions of diradicals than did HF. But restricted DFT breaks down with p-benzyne. People were just beginning to play with UDFT and recognize the interpretation of Professor Dieter Cremer deserves more credit for this than anyone else. My contribution was recognizing that the high symmetry of p-benzyne allows for CC to work properly. But with lower symmetry systems, like pyridynium, CCSD gives wacky results but Bruckner orbitals remove some instabilities and so it works well.  

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