After undergraduate degrees in chemistry (1950) and chemical engineering (1951) from the Technion in Haifa, he started a Ph.D. in experimental physical chemistry, but shortly after traveled to Cambridge University on a British Council Scholarship and completed his Ph.D. (1957) under the aegis of pioneering computational chemist S. Francis Boys.
In 1967 he moved to a senior research position at Battelle Memorial Institute in Columbus, Ohio, United States.
In 1968 he also became a part-time faculty member at the department of chemistry at Ohio State University and moved there full-time in 1981.
[2] Shavitt's landmark achievements include being responsible for two of the first applications of the then newly available computer to chemistry; developing the Gaussian transform method[3] for calculating multicenter integrals of Slater-type orbitals; coining the concept of contracted Gaussian-type orbitals; the GUGA (Graphical Unitary Group Approach) to fast configuration interaction calculations; and major contributions to coupled cluster theory.
An International Conference, entitled Molecular Quantum Mechanics: Methods and Applications" was held in memory of S. Francis Boys and in honor of Isaiah Shavitt in September, 1995 at St Catharine's College, Cambridge, and the proceedings published as a special issue[4] of the Journal of Physical Chemistry.