Kristin D. Krantzman, Department of Chemistry and Biochemistry , College of Charleston

URL: www.cofc.edu/~kdk/kdk.html, E-mail: krantzmank@cofc.edu

• What is Molecular Dynamics Simulation? In our group, we perform experiments on the computer using the method of molecular dynamics simulation. Molecular dynamics is a sophisticated game of billiards where the atoms are the 'balls' and move according to classical equations of motion. The key to building a viable model is to use forces that describe the appropriate chemistry. Details of the method are explained in Barbara J. Garrison, "Molecular Dynamics Simulations of Surface Chemical Reactions", Chem. Soc. Reviews, Vol. 121, 155-162 (1992). Animations of the motions of the atoms as they move in time can be created from the simulations. We use the method to study how processes between gaseous atoms and solids occur on a microscopic level.
• Our Research: Our research at the College of Charleston has focused on performing molecular dynamics simulations to study two types of gas-surface processes: 1) silicon-fluorine etching and 2) keV bombardment of organic films on metal substrates.
• Undergraduate Students: Twenty-one students have been involved in our undergraduate research program in theoretical chemistry. These students have gone on to pursue a variety of career options. The majority of have gone on to either graduate school or school for a medical profession. Others have gone on to work in environmental labs, to teach chemistry in high school and to design software in the high tech industry.

 From left to right: Bryan Green, Alema Galijatovic, Ronnie Barth, Tim Kenny, Adam Darcy

• Collaborators: The research on silicon-fluorine etching has been done in collaboration with another chemistry professor at an undergraduate institution, Tracy A. Schoolcraft at Shippensburg University. We met through John Stevens at the Council on Undergraduate Research. Tracy did her pH.D work with Barbara J. Garrison at Penn State. We have worked with Barbara J. Garrison since the summer of 1995 on molecular dynamics simulations of organic SIMS. We also have collaborated with Ken Jordan at the University of Pittsburgh on using quantum calculations to understand gas-surface reactions.
• Application to Silicon-Fluorine Etching: Silicon-fluorine etching is thought to occur by reactions between incoming gaseous fluorine atoms and Si_xF_y adsorbates on the silicon surface. An example is the reaction between F(g) and SiF₃(a), which react through an S_N2-like mechanism to form gaseous SiF₄. Click on the figure below to see an animation of the reaction (197 kB QuickTime Movie): 

Application to Cluster Organic SIMS: Our simulations show that the nature of the substrate is an important factor for cluster projectiles to be effective. The projectile SF₅ is able to break apart within the open lattice of the silicon substrate, which leads to a greater number of intact molecules ejected from the surface. Click on the figure below to see an animation of the bombardment process (2.9 MB AVI file):

• Representative Publications:

R. Zaric*, B. Pearson*, K.D. Krantzman, and B.J. Garrison, "Molecular Dynamics Simulations to Explore the Effect of Projectile Size on the Ejection of Organic Targets from Metal Surfaces", Int. J. Mass Spectrom. Ion Process. 1998, 174, 155-166.

J.A. Townes*, A.K White*, E.N. Wiggins*, K.D. Krantzman, B.J. Garrison and N. Winograd, "Mechanism for Increased Yield with the SF5+ Projectile in Organic SIMS: The Substrate Effect", J. Phys. Chem. A, 1999, 24, 4587-4589.

B. J. Garrison, A. Delcorte and K. D. Krantzman, "Molecule Liftoff from Surfaces", Accts. Chem. Res., 2000, 33, 69-77.

•  Acknowledgements: Financial support by the Research Corporation, the Petroleum Research Fund, and the National Science Foundation are gratefully acknowledged.