## Charlotte FischerGeneral Physics, Subatomic Particles, Optics, Biophysics, Theoretical PhysicsInternationally recognized for her software for calculating atomic structure, and for research in atomic structure theory. |

As a Master's student in applied mathematics, Charlotte Froese Fischer spent the summer of 1954 punching numbers about radio waves into a desk calculator at the Radio Physics Division of Canada’s National Research Council. That experience taught her something that would shape her entire career: many physics problems require extensive calculation.

Fischer has parlayed that understanding into an international reputation for research in atomic structure theory, notably for developing software that makes calculations about atomic structure. Originally a mathematician and chemist, Fischer also became a physicist and computer scientist in her quest to solve mathematical equations that describe how electrons behave in atoms. As a young UBC professor in 1963, she was the first woman scientist to be awarded the Alfred P. Sloan Foundation Research Fellowship.

Fischer’s computer programs are so accurate that she was able to predict the existence of a negatively charged calcium ion before such an ion had been detected experimentally. Fischer’s prediction was based on theoretical calculations of electron energy states in calcium, and was later shown to be correct when experimental results showed that negative calcium ions existed. For her work on calcium ions and related work, Fischer became a Fellow of the American Physical Society in 1991.

Physicists use equations to describe phenomena such as how electrons move, but the equations are often too complex to solve. Fischer uses a mathematical technique called numerical methods to solve such complex equations. Numerical methods represent a complex equation using a large number of simple but linked equations. The equations are simple enough to solve, and modern computers are powerful enough that they can perform the thousands of computations needed to arrive at an answer to the original equation.

Fischer started her teaching and research career in Canada, first at the University of British Columbia (1957–1968) and then at the University of Waterloo (1968–1975). At both universities, Fischer was instrumental in building computing science courses into the curriculum. Since 1974, Fischer has been a university professor at Penn State University and then Vanderbilt University, and most recently a guest researcher at the National Institute of Standards and Technology.

Fischer has produced a large body of published work. She has written over 250 scientific papers, including an early paper on her now-famous MCHF (Multi-Configuration Hartree-Fock) computer program that has been named a “Citation Classic” because it is cited so frequently by other researchers. She has written a book about computational atomic structure and a biography of her PhD supervisor and mentor, British mathematician Douglas R. Hartree. The results of Fischer’s research into atomic systems have been collected in a database showing electrons’ energy levels, lifetimes, and transition probabilities at http://atoms.vuse.vanderbilt.edu.

Sources: http://www.vuse.vanderbilt.edu/~cff/cff.html;

http://www.vuse.vanderbilt.edu/~cff/Reminiscence_CFF.pdf;

http://www.pnl.gov/energyscience/11-00/people.htm; Photo: http://physics.nist.gov/Divisions/Div842/Gp1/fischer.html