Frederick Seitz, the theoretical physicist who played a key role in founding the field of condensed matter physics but who may be better known for his roles as a government advisor and as the president of the National Academy of Sciences and Rockefeller University, died Sunday at a nursing home in New York City. He was 96.
No cause of death was announced by the university.
In recent years, Seitz had become controversial as a doubter of man-made global warming and for his efforts at channeling tobacco industry funds into medical research.
He was one of the "founding fathers" of condensed matter physics, said physicist Marvin Cohen of UC Berkeley. "He was a very important influence when the field was growing at a rapid rate."
Condensed matter physics, originally called solid-state physics, involves the properties of bulk substances, such as a lump of silicon, as opposed to those of individual atoms. The field has blossomed in the last two decades with the advent of new materials with special properties, such as better photovoltaic cells and ever smaller memories for computers.
But the field was created by researchers like Seitz.
In the early 1930s, while he was a graduate student at Princeton University, Seitz and his mentor Eugene P. Wigner were the first to calculate the physical properties of bulk sodium based on the known properties of sodium ions.
Their technique, known as the Wigner-Seitz method, was later used by other researchers to calculate the energies of the so-called band gaps that electrons jump over to conduct a current in semiconductors -- the basis of the transistor -- and is considered the catalyst for the formation of solid-state physics in the United States.
In 1940, Seitz published the seminal text "The Modern Theory of Solids," which was the bible of the field for many years, according to Cohen.
Seitz's subsequent research involved the theory and properties of crystals and the diffusion of atoms into crystalline structures.
By the late 1950s, however, his major scientific contributions had ended as he moved more fully into administrative positions, first as chairman of the governing board of the American Institute of Physics, then as science advisor to the North Atlantic Treaty Organization.
In 1962, Seitz was elected president of the National Academy of Sciences, a part-time job that was nonetheless very time-consuming. He played a crucial role in restructuring the presidency into a full-time position and was the first to accept a term in that role.
