CodesHow some of the earlier band structure calculations were done:
... all went smoothly until I had to face up to the problem of factoring high-order secular equations. I knew how to do this by hand, but the task was time-consuming, and it was necessary to check and recheck the factoring to make sure no errors were made. It then occured to me that my mother could help me with some of this work. I had read about the Hartrees — how the younger Hartree (Douglas R.) had been aided by his father (William), who was a retired railroad engineer and enjoyed doing “sums” on a desk calculator. I showed my mother how to set up the OPW secular equations and how to factor them, and she agreed to do some of this in her spare time ...
Frank Herman, Physics Today, June 1984, pp. 56-63