About

Prof. Robert J. Harrison is a theoretical chemist and expert in high-performance computing. He is a professor in the Applied Mathematics and Statistics department and the founding Director of the Institute for Advanced Computational Science (IACS) at Stony Brook University. Dr. Harrison's research interests focus on accurate calculations on large systems and heavy elements using advanced numerical and computational techniques. His academic background includes undergraduate and postgraduate degrees obtained at Cambridge University, England. He has worked as a postdoctoral research fellow at the Quantum Theory Project, University of Florida, and the Daresbury Laboratory, England, before joining the staff of the theoretical chemistry group at Argonne National Laboratory in 1988. In 1992, he moved to the Environmental Molecular Sciences Laboratory of Pacific Northwest National Laboratory, where he led the development of NWChem, a computational chemistry code for massively parallel computers. He has held joint faculty appointments with UT/ORNL since 2002 and became director of JICS in 2011. Dr. Harrison has received several awards, including the 2002 IEEE Computer Society Sidney Fernbach Award, and his work on NWChem and MADNESS has been recognized by R&D Magazine R&D100 awards in 1999 and 2011. He also co-chaired the National Academies of Sciences, Engineering, and Medicine committee on Future Directions for NSF Advanced Computing Infrastructure to Support U.S. Science from 2017 to 2020.

Research topics

• Computer Science
• Programming language
• Geography
• Sociology
• Political Science
• Parallel computing
• Medicine
• Operating system
• Demography
• Environmental health
• Chemistry
• Visual arts
• Computational science
• Art
• Software engineering
• Engineering
• Data science
• Mathematics
• Physics
• Computational chemistry
• Pathology
• Virology
• Simulation
• Nanotechnology

Selected publications

• Multiresolution Analysis using Data-Flow Programming

  Zenodo (CERN European Organization for Nuclear Research) · 2026-02-18

  articleOpen accessSenior author

  Presentation at WAMTA'26 on Multiresolution Analysis using Data-Flow Programming

  PublisherDOI

• Multiresolution Quantum Chemistry: Nonlinear Response Properties at the Basis Set Limit

  Journal of Chemical Theory and Computation · 2026-05-15

  articleSenior authorCorresponding

  We benchmark the accuracy of Dunning correlation-consistent Gaussian basis sets for computing frequency-dependent second-order hyperpolarizabilities relevant to second-harmonic generation (SHG), using multiresolution analysis (MRA) as a reference. Basis set errors are analyzed using a unit-sphere representation of the effective hyperpolarizability vector, enabling direct assessment of directional error structure. We introduce a relative RMS total error metric that integrates directional deviations over the unit sphere and complement it with signed projection errors that distinguish over- and underestimation. Unsupervised clustering based on these signed directional metrics reveals four distinct convergence behaviors across a set of 68 molecules. Unit-sphere visualizations of representative systems show that basis set errors are often highly anisotropic and localized along specific bond directions, even when global error measures appear small. Doubly augmented basis sets consistently outperform singly augmented ones, and core-polarization functions are required for uniform convergence in second-row systems. Overall, this work demonstrates that directional analysis combined with clustering provides a robust framework for understanding basis set convergence in nonlinear optical response properties.

  PublisherDOI

• Multiresolution Analysis using Data-Flow Programming

  Open MIND · 2026-02-18

  articleSenior author

  Presentation at WAMTA'26 on Multiresolution Analysis using Data-Flow Programming

  DOI

• Use of CIMOSA and systems thinking to document and inform the design and development of car engine production systems

  2026-02-11 · 2 citations

  article

  General enterprise engineering requirements are reported that arose during the design and production engineering of a range of component-based car engines. This needed teams of engineers from a global consortium of companies to currently resource multiple threads of complex engineering processes over an approximate four year timeframe. This paper characterizes the enterprise engineering requirements observed and provides a rationale for specifying, developing and using a new approach to Multiple Process Modelling (MPM). MPM unifies and extends the use of a pre-existing selection of enterprise modelling concepts, architectures and tools. Particularly MPM unifies the use of CIMOSA, Systems Thinking methods and tools and a workflow tool. MPM is under ongoing development and testing in relation to the requirements outlined and related large scale systems engineering problems faced by the global consortium.

  PublisherDOI

• Characteristics of California Engineered Stone Countertop Fabrication Workers Undergoing Lung Transplantation

  American Journal of Respiratory and Critical Care Medicine · 2025-05-01

  article

  Abstract RATIONALE Over one thousand cases of silicosis have been identified worldwide among workers who fabricate engineered stone (ES) countertops. These cases are notable for young age at onset and severity and rapid progression of disease; some require lung transplantation. We sought to describe characteristics of California ES countertop fabrication workers who have undergone lung transplantation for silicosis. METHODS We identified cases of ES-related silicosis through statewide multi-source surveillance, including data from a statewide database of hospital discharges, electronic medical record surveillance, and direct reports from clinicians and others. Cases were confirmed and transplant and vital status determined via medical record review. Demographic and transplant-related characteristics were obtained from hospital discharge data or abstracted from medical records. RESULTS As of October 2024, 213 cases of ES-related silicosis have been identified in California, including at least 13 workers who have died (6% of all cases). At least 50 patients (23%) have been referred for lung transplant; 6 were deemed ineligible, 19 are undergoing evaluation or awaiting transplant, and 25 (12%) have undergone lung transplantation. Among those who underwent lung transplant, all were men, and 96% were Latino. Median age at diagnosis was 48 years, and median age at transplant was 49 years (interquartile range [IQR] 42-52), with median time from diagnosis to transplant of 2 years (IQR 1-3). Two patients died following lung transplant. Those with data available had a median of 15 years of occupational exposure to silica dust (IQR 10-20). 75% were covered by Medi-Cal, California's Medicaid program, while 25% had private insurance coverage.CONCLUSIONS A high percentage of California workers with ES-related silicosis have undergone lung transplantation, most within a short timeframe following diagnosis, reflecting the severity and rapid progression of disease in patients with engineered stone exposure; the short diagnosis-to-transplant interval may also reflect delays in initial diagnosis. It is possible that additional patients have undergone lung transplantation, as we do not systematically track outcomes following initial case confirmation. The need for transplants in this population poses a significant health equity issue, as many workers with ES-related silicosis are Latino immigrants who may face barriers to health care access and eligibility for transplant. In addition, though silicosis is an occupational disease, none of the workers for whom data were available were covered by workers’ compensation insurance; in most cases, the costs of lung transplantation and other medical care were covered by public insurance.

  PublisherDOI

• Silicosis Surveillance in California, 2019–2024: Tracking an Epidemic

  American Journal of Public Health · 2025-09-04 · 3 citations

  articleOpen access

  Objectives. To characterize the nature, burden, and trends of silicosis among California workers, including workers with engineered stone exposures. Methods. We conducted multisource public health surveillance and generated descriptive statistics, compared engineered stone cases to cases with other silica exposures, and examined the utility of various data sources for silicosis surveillance. Results. We received 1817 reports of possible silicosis for 648 individuals from 2019 to 2024 and confirmed 296 (46%) cases, including 243 (82%) associated with engineered stone exposures. Engineered stone cases were more likely to be younger, men, Latino, and from Los Angeles County than were non–engineered stone cases. Of engineered stone cases, at least 15 (6%) were known to have died, and 60 (25%) were referred for lung transplant, including 30 (12%) who received transplants. There was limited overlap between reporting mechanisms. Conclusions. Multisource surveillance was effective for identifying a large number of individuals with silicosis, including people exposed to engineered stone. Outcomes were severe, and many patients had advanced disease. Results illustrate that worker screening and silica exposure mitigation are essential to prevent morbidity and mortality in the engineered stone countertop fabrication industry. ( Am J Public Health. 2025;115(11):1913–1921. https://doi.org/10.2105/AJPH.2025.308225 )

  PublisherOA PDFDOI

• Pulmonary Fibrosis Mortality by Industry – California 2017-19

  American Journal of Respiratory and Critical Care Medicine · 2025-05-01

  article

  Abstract Background The risk of developing pulmonary fibrosis (PF) increases among those occupationally exposed to vapors, dust, gas, and fumes (VGDF), as demonstrated by multiple retrospective case-control studies of university-based PF registries. Recruitment biases, sparse exposure data, and minimal clinical measures limit previous exposure studies in PF. To describe occupational PF mortality among all ever-employed Californian residents, we analyzed the multiple cause-of-death data from 2017-2019. Methods We analyzed the multiple cause-of-death data in the California Electronic Death Registration System (Cal-EDRS) from 2017-2019. We defined subjects as decedents aged ≥18 years at death with pulmonary fibrosis (ICD J84.1) listed as any cause of death. U.S. Census Industry Codes (2019) were assigned to decedents’ death certificate free text for “usual industry” using a machine learning-based system, the National Institute for Occupational Safety and Health (NIOSH) Industry and Occupation Computerized Coding System (NIOCCS). We included decedents with free text responses that indicated no employment history, homemaker, or student as “unemployed.” Proportionate mortality ratio (PMR) was defined as the observed number of deaths from PF in a specified industry, divided by the expected number of deaths from PF. The expected number of deaths was the total number of deaths in an industry multiplied by a proportion defined as the number of PF deaths in all industries, divided by the total number of deaths in all industries. Results Among 800,656 decedents, 10,104 (1.3%) had PF listed on the death certificate. The median age of death for those with PF was 80 years (IQR 71-87), and 47% were female. The racial/ethnic background of the decedents with PF was 5915 (59%) White, Not Hispanic; 2563 (25%) White, Hispanic; 1043 (10%) Asian/Pacific Islander; 447 (4%) Black; and 78 (1%) Native American/Indigenous. Significantly elevated PMRs were seen in the industry categories of utilities (1.28, 95% CI 1.04-1.52), public administration (1.22, 95% CI 1.12-1.31), agriculture (1.20, 95% CI 1.07-1.33) and manufacturing (1.10, 95%CI 1.04-1.17). Those categorized as never employed had a significantly decreased PMR of 0.48 (95% CI 0.41-0.55). Discussion Using data from the Cal-EDRS, we found elevated PMRs for PF in particular industries within a diverse patient population. Elevated PF mortality among workers in specific industries and occupations underscores the importance of examining specific risk factors for PF to target interventions and prevent severe PF from developing. Additionally, using population-level death registries enables examining a more diverse population when compared to university-based disease registries, which over-represent white and male patients.

  PublisherDOI

• Concurrent Collections: An Overview

  Lecture notes in computer science · 2025-01-01

  book-chapter
  PublisherDOI

• Thallium Exposure Secondary to Commercial Kale Chip Consumption: California Case Highlights Opportunities for Improved Surveillance and Toxicological Understanding

  International Journal of Environmental Research and Public Health · 2025-08-07 · 2 citations

  articleOpen access

  BACKGROUND: Thallium is a metal that is ubiquitous in our natural environment. Despite its potential for high toxicity, thallium is understudied and not regulated in food. The California Department of Public Health was alerted to a household cluster of elevated urine thallium levels noted among a mother (peak 5.6 µg/g creatinine; adult reference: ≤0.4 µg/g creatinine) and her three young children (peak 10.5 µg/g creatinine; child reference: ≤0.8 µg/g creatinine). OBJECTIVES: This case report identifies questions raised after a public health investigation linked a household's thallium exposure to a commercially available food product. We provide an overview of the public health investigation. We then explore concerns, such as gaps in toxicological data and limited surveillance of thallium in the food supply, which make management of individual and population exposure risks challenging. METHODS: We highlight findings from a cross-agency investigation, including a household exposure survey, sampling of possible environmental and dietary exposures (ICP-MS analysis measured thallium in kale chips at 1.98 mg/kg and 2.15 mg/kg), and monitoring of symptoms and urine thallium levels after the source was removed. We use regulatory and research findings to describe the challenges and opportunities in characterizing the scale of thallium in our food supply and effects of dietary exposures on health. DISCUSSION: Thallium can bioaccumulate in our food system, particularly in brassica vegetables like kale. Thallium concentration in foods can also be affected by manufacturing processes, such as dehydration. We have limited surveillance data nationally regarding this metal in our food supply. Dietary reviews internationally show increased thallium intake in toddlers. Limited information is available about low-dose or chronic exposures, particularly among children, although emerging evidence shows that there might be risks associated at lower levels than previously thought. Improved toxicological studies are needed to guide reference doses and food safety standards. Promising action towards enhanced monitoring of thallium is being pursued by food safety agencies internationally, and research is underway to deepen our understanding of thallium toxicity.

  PublisherOA PDFDOI

• Recruitment Challenges for Physician Training in Occupational and Environmental Medicine

  Journal of Occupational and Environmental Medicine · 2025-03-27 · 1 citations

  articleSenior author

  OBJECTIVE: The aim of the study was to characterize experiences of current and recent trainees of occupational and environmental medicine (OEM) to inform recruitment. METHODS: In fall 2023, a survey was sent to 115 current OEM residents and approximately 250 alumni from the previous 5 years regarding demographics, career motivations, and experience with application/training process. RESULTS: The response rate was 54% (62/115) for current residents and approximately 22% (56/~250) for alumni. Only 20% learned about OEM before internship and 41% applied to only one program. The top 3 features of training programs were quality/support of faculty, research opportunities, and family/geographic preference. Eighty-four percent support a combined/paired internship program. CONCLUSIONS: The survey highlights challenges in recruitment to OEM, suggesting the need for increased outreach to medical students, opening/reopening programs in new geographic areas, and exploring combined/paired internship programs.

  PublisherDOI

Recent grants

• Collaborative Research: Cyber-infrastructure and Research Facilities: Chemical Computations on Future High-end Computers

  NSF · $887k · 2006–2012

• MRI: Acquisition of a computer system for Research and Education – Seawulf

  NSF · $485k · 2022–2025

• MRI: Acquisition of SeaWulf - A Reconfigurable Computer System for Research and Education

  NSF · $1.4M · 2015–2018

• Collaborative Research: SI2-SSI: Task-Based Environment for Scientific Simulation at Extreme Scale (TESSE)

  NSF · $623k · 2015–2019

• California Occupational Safety and Health Surveillance

  NIH · $15.8M · 2021–2026

Frequent coauthors

• Jennifer Flattery

  61 shared

• George I. Fann

  Oak Ridge National Laboratory

  47 shared

• Kenneth D. Rosenman

  Michigan State University

  44 shared

• Mary Jo Reilly

  Michigan State University

  42 shared

• Elise Pechter

  38 shared

• Jeffrey A. Nichols

  36 shared

• David Valiante

  New Jersey Department of Health

  35 shared

• David A. Dixon

  University of Alabama

  35 shared

Education

• Ph.D., Computer Science

  University of California, Berkeley

  1990

• M.S., Computer Science

  University of California, Berkeley

  1985

• B.S., Computer Science

  University of California, Berkeley

  1983

Awards & honors

• 2002 IEEE Computer Society Sidney Fernbach Award
• R&D Magazine R&D100 awards in 1999 and 2011