Letter to the Editor

Dear Mike,

I read your editorial in the first 2025 issue of the IUCr Newsletter with interest, especially the paragraph about Istvan Hargittai’s 1999 interview of Dick Marsh. I was surprised by the use towards the end of that paragraph of the term PCI (Practicing Crystallographic Idiot) in a sense very different from that which I had long understood.

I am quite sure that the term was invented by Jim Ibers. In his ACA memoir (Ibers, 2020; https://acra.memberclicks.net/jim-ibers-articles), Jim wrote:

"I don’t remember why I was there but around 1962 I attended a meeting of about 12 people in the French Alps overlooking Lake Geneva. In attendance were Martin Buerger, Jose and Gabrielle Donnay, and several high-level theorists, including Hans Wondratschek. The purpose of the meeting was to organize the space group information for the new International Tables. I, as the 'pci' — the practicing crystallographic idiot — made two important contributions. I kept the theorists from making 'c' the sole monoclinic symmetry axis and I had them include the necessary information to define a unique unit cell."

As Jim’s PhD student (1969-72), I can say with confidence that he was no idiot (e.g. he wrote early code for dispersion corrections and group refinements). Even so, he might well have felt out of his depth when Wondratschek et al. discussed the mathematics of symmetry (see some of the text sections in Vol. A of International Tables). The term PCI reflects Jim’s sense of humor. As he used the term it implied somebody who was very good at crystallography (Jim most certainly did not consider himself an idiot) but who left to others the mathematics that some might view as arcane. In his role as a PCI, Jim aimed to make Vol. A useful for the average crystallographer, and he tried to get the mathematicians to describe difficult concepts in words that more ordinary crystallographers could understand. The application of the term PCI to crystallographers who have made a basic mistake, such as refining a structure in a space group of too-low symmetry, came much later. That application misses the dry humor of the original meaning.

Let me add that Dick Marsh was delighted when he himself was 'Marshed' [see Marsh & Sparks (2001)]. As the co-editor who handled that submission, I well remember the pleasure Dick took in having his mistake uncovered. Dick was a merry soul — not at all pompous or stern — but he didn’t like unnecessary mistakes, and so was happy to laugh about his own unforced error. 

References

Marsh, R. E. & Sparks, R. A. (2001). Acta Cryst. B57, 722.

Ibers, J. (2020). ACA Living History, RefleXions.