FAYETTEVILLE, Ark. — In 1969, Peter Pulay wrote a paper that was to change permanently the way scientists study atoms and molecules, the basic matter of the universe. His research would help solve one of the most urgent tasks in quantum chemistry: finding an accurate method for calculating the electronic structure, size and shape of large molecules.

Since the 1920s, researchers had used an equation developed by Erwin Schrödinger to describe the motion of electrons and nuclei. But such equations, enormously complex and time-consuming to calculate, meant that only the simplest molecules could be measured.

The gradient method he outlined, published in The Journal of Molecular Physics, proved to be a pioneering advance in the effort to determine the geometry of large, biologically important molecules. From 1980 to 1997, Pulay’s contribution was cited in the work of other scientists 3,303 times, earning the title of a "Citation Classic" from the Institute of Scientific Information in recognition of its importance to the entire scientific community.

He has received numerous international awards as well, from the highest honor in his field, the Medal of the International Academy of Quantum Molecular Sciences in 1982, to the Alexander von Humboldt Senior Scientist Award in 1995. Pulay joined the University of Arkansas faculty in 1982 as a professor in the Department of Chemistry in the Fulbright College of Arts and Sciences.

But one of the most meaningful awards in his life was bestowed in May, when Distinguished Professor Pulay returned to his native Hungary. Declaring him "a most learned man, a doctor and professor of the natural sciences," Eotvos University in Budapest, his alma mater, awarded Pulay an honorary doctorate.

"They have a very good theoretical chemistry department there," said Pulay. "Also, I was able to see my father and visit with colleagues again."

A theoretical chemist, Pulay has long believed that the advent of powerful computers in the 1980s meant that scientists could uncover even more effective techniques for measuring the properties of chemical systems. Over the years, he has assembled dozens of computers in his laboratory, and with the help of coworkers, has written the software that enables users at both universities and commercial laboratories around the world to simulate chemical systems on an ever increasing scale.

"The possibility exists," said Pulay, "of using calculations to predict the properties of all matter, except light."

Pulay will extend the scope of his ongoing research with support from a new $401,000 NSF grant awarded in July. Since 1983, he has won six three-year NSF grants in addition to funding from the Department of Defense, the Petroleum Research Fund, IBM and the Air Force Office of Scientific Research. In 1992, he received a creativity award from the NSF, given to only a handful of the most creative investigators. Recipients are granted an automatic extension in funding to five years without being required to submit an additional proposal.

The latest grant will allow Pulay to explore a topic fairly new to chemists, quantum or wave mechanics.

"In traditional quantum chemistry, one starts with the atomic function," explained Pulay. "But atomic functions are complex and time consuming to calculate. The alternative is to use simple waves, or sign and cosign functions, which are very regular. Since they don’t have any obvious bearing to a molecule, you need a large number of them to build up the wave function, which essentially determines everything in an atomic system. Simple waves are used to describe electrons that move freely in metals and semiconductors, but their application for describing molecules has been hampered by the fact that up to millions are required for accurate modeling.

"The goal is essentially the same, only the mathematical techniques are different."

Since no single computer is powerful enough to work out these calculations, Pulay and his coworkers have linked together a number of inexpensive but powerful personal computers. The combination has outperformed a Cray supercomputer at a fraction of the cost.

"I think that the future of scientific computing lies in applying mass-produced inexpensive hardware in a massively parallel way," said Pulay. Pulay has been collaborating with Professor Amy Apon of the Computer Science and Computer Engineering Department to develop parallel computing, while the custom-built computers he and coworkers have assembled have transformed his laboratory into an electronics workshop.

Pulay’s research area has been targeted by the National Science Foundation as a "grant challenge problem," meaning that successful results would have a major impact on society.

Applications include molecular "switches" that act like transistors but are in reality a single molecule or a few molecules, which could produce much faster computers. Being able to predict when two molecules fit together would provide a major boost to current nationwide research efforts to assemble "designer" molecules, capable of curing diseases by blocking the enzymes that allow viruses to invade the body. The virtually infinite number of molecular combinations make empirical testing nearly impossible.

"Other potential applications include describing the chemical reactions that take place in the stratosphere and are responsible for the destruction of the ozone layer, or modeling the properties of pollutants," said Pulay.

Among his fellow scientists, Pulay is considered one of the top 20 researchers in his field internationally. "When you consider the many thousands alone in theoretical chemistry, in universities from Russia to China and across the Western hemisphere, that’s an enormous accomplishment," said Don Bobbitt, Associate Dean for Research in Fulbright College.

The one researcher who has contributed most to the basic understanding of electronic and molecular structure is John Pople, who won the Nobel Prize in 1998 for his work extending over three decades at Carnegie-Mellon. In awarding Pople the Nobel, the prize committee commended Pople for his effective calculation "of these derivatives based on earlier developments by Peter Pulay."