Paul started his career in molecular and materials modeling as a graduate student with Prof. Henry F. “Fritz” Schaefer, III, at the University of California, Berkeley, working on some of the early codes for direct configuration interaction (CI) and calculating first and second derivatives of the energy. These codes, which allowed better calculations and faster ways to find structures and calculate vibrational spectra, started Paul’s interest in developing better and better tools for simulating molecules and materials, as well as his life-long interest in harnessing the ever increasing power of computers to science. At the time, in the 1980s, computers were much more limited than they are now — a million or more times slower! However, they could nonetheless handle interesting scientific questions, and the growth has both been a challenge and exhilarating.
After departing Berkeley, Paul held an NAS/NRC postdoc at the Ballistics Research Lab (now ARL) in Aberdeen, MD, and then joined the Theoretical Division at Los Alamos, continuing his work developing quantum chemistry methods and implementing them in a package for general use. He then switched careers, joining BioDesign, one of the early commercial companies developing and selling molecular modeling software, at the time predominantly forcefield-based molecular dynamics (MD) codes. At BioDesign, Paul broadened his scope to include MD and forcefields as well as computer graphics, working with Prof. William “Bill” Goddard, III, of CalTech, who was one of the founders of BioDesign. After a few years Paul migrated to Biosym, another modeling company, to manage both their commercial MD code, Discover, as well as the rest of the computational codes including DFT, distance geometry and codes for calculating electrostatics. Paul became heavily involved with polymer simulations as well as DFT calculations for inorganic materials during his time at Biosym. Over time, Biosym merged with MSI, which was the company originally called BioDesign, and eventually became Acclerys and more recently Biovia.
As these mergers occurred, Biosym/MSI pulled back from the materials market, so Paul left with Dr. John Harris to start Materials Design in 1998. Materials Design focussed heavily on materials simulations and databases, so for the next 18 years Paul had a hand in every aspect of commercial modeling, from code development to graphics to user interfaces and workflows, as well as a considerable amount of innovative science using the tools he was building. This experience rounded out Paul’s background, which include quantum chemistry for molecular systems, forcefields and MD for drug design as well as for polymers, and finally materials simulation using either forcefield approaches such as the embedded atom method (EAM) of periodic DFT with codes such as VASP.
In 2017, Paul brought this wealth of experience to MolSSI as the lead software scientist.