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Dr. Robert LeRoy.Courtesy of the LeRoy family

Robert J. LeRoy, one of Canada’s foremost theoretical chemists, followed his father into academia and became a learned giant within a highly specialized field. His work focused on the behaviour of molecules and atoms, particularly the forces occurring among them. When asked to explain the complexities of his profession to laypeople he was known to say: “I study the sex life of molecules.”

Mischievously good humoured, the University of Waterloo professor inspired and mentored thousands of young scientists. One page of the chemistry textbook currently in use in Ontario high schools is devoted to the LeRoy radius, a technique for mathematically defining the radius of a small molecule, which is key to understanding the forces at work both inside and outside of that boundary.

His work on predictive computer modelling resulted in many honours and awards including the Rutherford Memorial Medal in Chemistry by the Royal Society of Canada (1984) and the J. Heyrovsky Honorary Medal for Merit in the Chemical Sciences by the Academy of Sciences of the Czech Republic (1995).

During his career, the internationally acclaimed scientist grappled with problems in theoretical and computational chemical physics, while also dealing with serious health challenges. In his 40s, Mr. LeRoy was diagnosed with multiple myeloma, a relatively rare cancer in someone so young. When chemotherapy caused his hair to fall out, he decided to adopt a new look – shaving his head and piercing his ear. University of Waterloo colleagues and students got together to present him with an earring made out of a bolt. He wore it with pride.

“He was able to bring light to everything he did,” his daughter Sylvia said. “He was a kind of medical marvel.” After he received radiation treatment and a bone marrow transplant for a tumour on his spine, his mobility was severely impaired – but leg braces, two canes and determination kept him walking. He went to his lab almost every day and rarely missed maple syrup season on the family tree farm near Wilberforce, in northeastern Ontario. At the Symposium on Chemical Physics, hosted annually at the University of Waterloo, Mr. LeRoy created a tradition by hosting a raffle to give away a bottle of his family’s maple syrup. Just prior to his 68th birthday, he underwent heart bypass surgery. Mr. LeRoy died six years later, at the age of 74, on Aug. 10 at his home in Waterloo, Ont.

A major force at international meetings, Mr. LeRoy was renowned for having a brilliant mind as well as a distinctive fashion sense, often wearing loud ties and tapestry jackets. “He had a very bold sartorial style,” said his niece Jennifer, a research fellow at Oxford University. “Then again” she added, “he was also colour-blind.

Born in Ottawa on Sept. 30, 1943, Robert James LeRoy was the second of four sons born to Donald James (D.J.) LeRoy and Lillice (née Read). At that time, his father was a research scientist at the National Research Council. A year after Robert’s birth, his father took a post at the University of Toronto, eventually working his way up to head of the chemistry department. One of the people the elder Mr. LeRoy hired as a lecturer was John Polanyi, who would go on to win the 1986 Nobel Prize in chemistry.

Meanwhile, Robert attended Allenby Public School, then North Toronto Collegiate Institute, where he graduated in 1961. His brother John recalled that Robert was a brilliant student.

"I remember in his final year of high school,” John said, “… he wrote exams in three different types of math. In two of them he received a perfect mark of 100 per cent, while in the other he received a little less. He knew where he had made a careless error and he lamented about it for weeks after. He knew he should have been perfect in all three.”

Mr. Polanyi remembers being warmly welcomed into the rambunctious LeRoy household of his boss, D.J., whose wife, Lillice, smoked a pipe and would later become a stockbroker.

"Robert, whom I came to know better as a student and later as a fellow scientist, was unmistakably a LeRoy,” wrote Mr. Polanyi via e-mail. “He exhibited indomitable courage and infectious joy in his creative life.”

When the LeRoy family would host faculty dinners at their home, Robert’s brothers would serve the food and focus on hospitality, but Robert made a point of talking to the professors, learning about their research and areas of interest. “I am sure that this contact with different chemistry professors helped to pique his interest in chemistry,” John said.

When Robert arrived at the University of Toronto, he immersed himself in the intensive stream of mathematics and chemistry, obtaining a bachelor of science in 1965 then, two years later, a master’s in chemistry.

One recreational activity he enjoyed was singing in the university choir, but it annoyed him when sheet music wasn’t treated with respect. A young Lithuanian political science student named Virginia Pusvaskis felt the same way and took the time after practice to pick up sheet music that had floated to the floor. The attraction between the two was intense and immediate. They married on July 22, 1967. The chemist completed his doctorate at the University of Wisconsin-Madison in 1971, before returning to Toronto for postdoctoral work in physics. Robert LeRoy’s family grew to include a son and three daughters, children to whom he was as devoted as he was to his work.

In an interview posted on his website he wrote, “My research was initially on experimental kinetics but I switched to the theoretic/computational area which has been my focus ever since. I really liked the hands-on part of experimental chemistry – building apparatus, putting together electronics, and glass-blowing vacuum lines, but I also grew to love even more the hands-on work of designing, and writing, and using computer codes to ask interesting questions about molecules. The latter won out.”

In the early days of computing, a modest-size program entailed a couple of thousand computer cards jam-packed into boxes which had to be lugged to the keypunch machine, the card reader, then back to the office. “Even theoreticians got their exercise,” Mr. LeRoy said.

It was never enough for Mr. LeRoy to understand the how. He strove to understand the why. His contribution to quantum mechanics allowed scientists to compile information on forces and structures of molecules that are not well known. He developed many essential computer programs, still in use worldwide, that aid in collecting experimental evidence. One example is computer code he developed that could, in turn, help others understand data that satellites collect to reveal the composition of Earth’s atmosphere. He wrote: “My basic satisfaction is not in seeing some explicit practical application, but rather in seeing that others use my methods and results, in the certain knowledge that farther down the knowledge ‘food chain’ it will have practical import.”

Mr. LeRoy leaves his wife, Virginia; son, Xander; daughters, Monika, Clara and Sylvia; brothers, John and Rodney; three grandsons; and a host of nieces and nephews.

“I had the privilege of being Bob’s niece and growing up under his influence,” Jennifer LeRoy said. “When I decided to become a scientist, he invited me to attend several conferences at Waterloo where I got to know his more professional side. He always said, ‘Don’t choose something because it’s easy – choose it because it’s challenging and worthwhile.’”

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