Dr. David Dixon
Pacific Northwest National Labs

EMSI Visiting Scholar
April 15-18, 2003

Seminar: "Computational Thermochemistry - From the Gas Phase to Solution"
Tuesday, April 15, 2003, 4:00 p.m., Interschool Lab, 7th Floor Schapiro CEPSR

The development of new theoretical methods, algorithms, and software which incorporates these advances on modern high performance, massively parallel computer architectures is leading to new insights into the behavior of molecules and to the use of simulation methods to replace expensive experiments. These new hardware and software developments promise to revolutionize the size and types of chemical systems that can be treated. We will describe how these advances in computational chemistry can be used for predicting the heats of formation of molecules including those of interest in combustion processes and in nitrogen chemistry. We will describe the prediction of the free energies of solvation of the proton, hydroxide anion, and electron in aqueous solution. We will describe the prediction of accurate fluoride affinities for use in establishing a Lewis acidity scale.

Seminar: "Computational Approaches to the Design of 157 nm Photoresists"
Thursday, April 17, 2003, 10:00 a.m., 340 Havemeyer Hall (Turro Group seminar)

Advances in methodology, software, and hardware now make it possible for computational chemistry to aid in materials design. The biggest obstacle to a practical F2 photolithography system for semiconductors is the development of new photoresist and pellicle materials that are transparent at 157 nm. We have been using time-dependent density functional theory (TD-DFT) to calculate the photoabsorption of molecules in the vacuum ultraviolet region to design such new materials. We have studied a wide range of fluorinated derivatives with a focus on norbornane derivatives and on linear alkanes. A key conclusion is that the excitation spectra in the region near 157 nm are dominated by Rydberg transitions. The ionization potential as represented by the HOMO energy may be useful to estimate the absorption in this region. In addition, to predicting photoabsorption behavior, we have also developed a computational approach to the prediction of Q-e parameters for free-radical copolymerizations based on DFT.

Information about Dr. Dixon's research interests is available at http://www.biomolecular.org/staff/dixon.html.