Applying Science

Jeff Hammond

(Page 2 of 3)

It was a heady introduction to the world of on-the-job training — one that Hammond relished.

“It was such an amazing experience to be in a work environment where, as opposed to academia, they actually have people whose job it is to help others do stuff they don’t know how to do,” Hammond says.  “The computer people there, along with Bert and (PNNL staff scientist) Karol Kowalski, taught me basically everything I know about compilers, parallel computing, debugging and Fortran.”

What he lacked in particulars, Hammond made up for in drive and broad quantum chemistry knowledge. After sadly leaving his new wife behind in Chicago, he settled into 90-hour work weeks fueled by lots of Mountain Dew.

His challenge was significant: Give NWChem the power to do highly accurate spectroscopy — to model the light emitted and absorbed by a molecule.

“Experimentalists study molecules spectroscopically,” Hammond says. “But most computer codes can’t calculate spectra directly.  This is a big problem and makes the models less useful as predictive tools.  What I did was give NWChem the ability to calculate the spectra of molecules based on their quantum chemical characteristics.”

Hammond spent his first month at PNNL on a steep learning curve — reading scientific papers, deriving equations and talking with Kowalski to develop a solid working understanding of coupled-cluster theory.  That’s a well-established theoretical physics tool for approximately solving the Schrödinger equation; this enables scientists to predict a molecule’s reactivity with other molecules or its response to a jolt from a laser beam.

“The math that we did can model the interaction of molecules with lasers,” Hammond says.  “But with a little more work it can also model the molecule’s interaction with magnetic fields.  This means modeling nuclear magnetic resonance, one of the most important tools biologists use to study the structure of large, complex proteins.”

With Kowalski, Hammond developed the specific code to implement the coupled-cluster theory in NWChem and subsequently spent a month debugging it so it could run effectively on supercomputers, including the one located at DOE’s National User Facility, the Environmental Molecular Sciences Laboratory at PNNL.

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