An appreciation

I was highly honored, stimulated, and grateful for the excellent symposium John Goddard, Fritz Schaefer, Leo Radom, Peter Schwertfeger, Richard Wong, Yoshihiro Osamura, and Kimihiko Hirao arranged in Hawaii, and now by the papers assembled in this special JCC issue by Gernot Frenking. But my gratification is more than personal, since these recognitions mark, along with many others not involving me, the status and glowing prospects of computational chemistry. But it took three decades of struggle before the current general acceptance was achieved. Those of you old enough to have lived professionally through this period were well aware of the high barrier to this acceptance among most of your chemical colleagues. Theoreticians had at least the support of their peer group where the research goals and developments were appreciated. But this group dismissed me as a “black box user” without even a basic knowledge of quantum chemistry. I became an outsider to my own peer group— the physical organic chemists—as well. This group who, in principle, should have embraced emerging theoretical methods, was (with a few notable exceptions) not at all interested in computational quantum chemistry at the time. Results obtained by computation were considered as being unworthy of serious consideration, even for their conceptual content. I remember well several occasions in the 1970’s attending conferences in Theoretical and in Physical Organic Chemistry, fortuitously scheduled in successive weeks. It was like being in two completely different worlds, unaware of each other’s existence. My talks did not appeal to either audience. I came to computational quantum chemistry via molecular mechanics in the late 1960’s. Interested in structures and energies, I was frustrated by the lack of needed experimental data. Molecular mechanics, which was based on the principles of “conformational analysis” (angle and torsional strain, non-bonded interactions, etc.) I had been teaching graduate students for fifteen years, was the method of choice. Our computer program, based on Ken Wiberg’s, was implemented and our first papers were published at the same time as Lou Allinger’s. These were the only practicable means, considering the main frame limitations and computer center CPU-time charges of 1970, of obtaining reliable energies and geometries of medium large organic molecules, at least for hydrocarbons for which force fields could be parameterized well. Lou and I continued as competitors in this area for only a few years. In 1981, a year after Lou founded JCC, I joined him as co-editor and then in the 1990’s as a colleague at the University of Georgia (initially even as a neighbor!). In 1968, I was invited to give a series of NSFsponsored Lectures at Mellon Institute (as it was named in those days). My general theme was carbocations, a topic then in its heyday. This brought me into close contact with John Pople, whom we had tried to lure to Princeton unsuccessfully when he was considering a move to the United States. My co-workers (including postdocs who had joined my group from Michael Dewar) and I, along with my Princeton colleague, L. C. Allen, already had some ab initio papers to our credit. But I was mesmerized and converted by John Pople especially upon learning about the emerging Gaussian 70 and his plans to develop quantum chemical programs as well as data evaluation strategies for general use.