About

Professor So Hirata received his B.S. (1994) and M.S. (1996) from The University of Tokyo and his Ph.D. (1998) from the Graduate University for Advanced Studies (Institute for Molecular Science) in Japan. He has held positions as a Visiting Scholar at the University of California, Berkeley, and a postdoctoral research associate at the University of Florida. He was a Senior Research Scientist at Pacific Northwest National Laboratory before becoming an Assistant Professor at the University of Florida, where he was promoted to Associate Professor in 2009. Professor Hirata joined the University of Illinois faculty in August 2010 as a Professor and an Alumni Research Scholar. Currently, he serves as the Marvin T. Schmidt Professor and a Blue Waters Professor, as well as a Beckman Affiliate Faculty. His research focuses on electronic and vibrational many-body theory for molecules, polymers, solids, and liquids, and on developing computer algebra for quantum chemistry. His work aims to push the limits of quantitative theories and computational technology to interpret and predict properties and transformations of various chemical systems, developing new mathematical methods and algorithms to make complex equations tractable for numerical solutions.

Research topics

• Physics
• Statistics
• Mathematics
• Computer Science
• Mathematical physics
• Quantum mechanics
• Chemistry
• Nanotechnology
• Engineering
• Biology
• Statistical physics
• Computational chemistry
• Materials science
• Computational science
• Management science
• Data science
• Simulation

Selected publications

• Abstract 4370014: Association of Inhaled Nitric Oxide with VA-ECMO Weaning and Short-Term Outcomes in ECPELLA Patients: A Retrospective Study

  Circulation · 2025-11-03

  article

  Background: Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) combined with the Impella left ventricular assist device (ECPELLA) has emerged as a promising strategy for cardiogenic shock. Inhaled nitric oxide (iNO) selectively reduces pulmonary vascular resistance, thereby lowering right ventricular afterload and improving right ventricular function. These effects suggest iNO may be beneficial during VA-ECMO weaning in ECPELLA patients. Research Question: This single-center retrospective study evaluated whether iNO therapy in ECPELLA patients was associated with VA-ECMO weaning and short-term outcomes. Methods: Between October 2018 and May 2025, 151 patients received ECPELLA support at our institution. Since 2022, iNO has been available and administered at the discretion of the attending physician. Primary outcomes were 30-day all-cause mortality, VA-ECMO weaning rate, and VA-ECMO duration. Secondary outcomes included changes in hemodynamic parameters and mechanical circulatory support flow, evaluated before and 24 hours after iNO initiation in the iNO group. Results: Of 151 patients, 64 received iNO therapy and 87 did not. There were no significant differences in age, sex, comorbidities, acute coronary syndrome, extracorporeal cardiopulmonary resuscitation (E-CPR), or initial lactate levels. Renal impairment was more prevalent in the iNO group. In that group, VA-ECMO flow significantly decreased 24 hours after iNO initiation, while pulmonary artery pressure, pulmonary artery pulsatility index, cardiac output, and Impella flow remained unchanged. The iNO group had a significantly higher VA-ECMO weaning rate (86% vs. 51%, p < 0.001) and longer VA-ECMO duration (6.3 [4.7–9.8] vs. 4.1 [2.0–6.2] days, p < 0.001). Kaplan–Meier analysis showed improved 30-day survival in the iNO group (45% vs. 38%, p = 0.030). Multivariate Cox analysis revealed E-CPR (HR: 1.66, 95% CI: 1.02–2.70, p = 0.040), eGFR (HR: 0.98, 95% CI: 0.97–0.99, p < 0.001), and iNO use (HR: 0.51, 95% CI: 0.32–0.81, p = 0.004) were significantly associated with 30-day mortality. Conclusion: In ECPELLA-supported patients, iNO was associated with higher VA-ECMO weaning rate and improved 30-day survival despite longer VA-ECMO duration. Prospective studies are needed to identify those who benefit most from iNO.

  PublisherDOI

• Performance of the spin-component-scaled methods for energy bands

  Molecular Physics · 2025-05-14 · 1 citations

  articleSenior authorCorresponding
  PublisherDOI

• Ultrafast Correlation Energy Estimator

  The Journal of Physical Chemistry A · 2025-09-10 · 1 citations

  articleOpen access

  A virtually no-cost method is proposed that can compute the correlation energies of general, covalently bonded, organic, and inorganic molecules (including conjugated π-electron systems) with a well-defined dominant Lewis structure at the accuracy of 99.5% of the near-exact values determined by the coupled-cluster singles, doubles, and perturbative triples [CCSD(T)] in the complete-basis-set (CBS) limit. This Correlation Energy Per Bond (CEPB) method assigns a partial correlation energy to each bond type (characterized by the identities of the two atoms forming the bond and its integer bond order) and to a lone pair, regardless of the bond length, bond angle, sp-hybridization, π-electron conjugation, ionicity, noncovalent interactions, etc. At its current stage, the method is mainly suitable for near-equilibrium geometries. The correlation energies per bond are determined by a fit to the CCSD(T)/CBS benchmarks. It can neither improve the equilibrium structures nor discern conformers or positional isomers, yet its accuracy for reaction energies rivals that of the second-order Møller-Plesset perturbation theory, which is far more expensive. Its promising performance underscores the possibility that surprisingly compact, chemically intuitive molecular fragments exist into which correlation energies can be partitioned, leading to various ultrafast correlation-energy estimators tailored to different purposes.

  PublisherOA PDFDOI

• New Dimension in <i>Ab Initio</i> Electronic Structure Theory: Temperature, Pressure, and Chemical Potential

  The Journal of Physical Chemistry Letters · 2025-04-04

  reviewOpen access1st authorCorresponding

  Ab initio electronic structure theory has transformed gas-phase molecular science with its predictive ability. In the attempt to bring such predictive ability to macroscopic systems and condensed matter, the theory must integrate quantum mechanics with statistical thermodynamics so that thermodynamic functions such as free energy, internal energy, entropy, and chemical potentials are computed as functions of temperature in a systematically converging series of approximations. A general, versatile strategy of elevating any ab initio electronic structure theory to nonzero temperatures is introduced and discussed.

  PublisherOA PDFDOI

• EPCO-31. CLINICALLY APPLICABLE MOLECULAR GROUPING OF INTRACRANIAL MENINGIOMAS BASED ON HIGH-RISK COPY NUMBER ALTERATIONS AND <i>NF2</i> /22Q STATUS

  Neuro-Oncology · 2025-11-01

  articleOpen access

  Abstract BACKGROUND The 2021 WHO classification of meningiomas incorporated molecular markers such as CDKN2A/B homozygous deletion and TERT promoter (pTERT) mutations as diagnostic criteria for grade 3 tumors. Although large-scale multi-omics studies have revealed the biological heterogeneity of meningiomas, their clinical implementation remains limited. METHODS This study included intracranial meningiomas surgically resected between 1999 and 2024. Whole-exome sequencing was performed to identify driver mutations and arm-level copy number alterations (CNAs). Tumors were stratified into three molecular groups based on eight high-risk CNAs (e.g., CDKN2A/B homozygous deletion, pTERT mutation, 1p/6q/10q/14q/18q loss, 1q gain) and NF2/22q status. Associations with recurrence-free survival (RFS) were evaluated using Kaplan–Meier analysis, log-rank tests, and Cox regression models. RESULTS A total of 487 patients with intracranial meningiomas were included. The median age was 57 years (IQR, 48–67), and 332 (69.9%) were female. Group A (NF2-mutant, no high-risk CNA), Group B (NF2-wildtype, no high-risk CNA), and Group C (high-risk CNA-positive) comprised 143, 198, and 134 tumors, respectively. RFS differed significantly across groups (p &amp;lt; 0.001), with Group C exhibiting the poorest prognosis—particularly in WHO grade 1 tumors following gross total resection (GTR). In multivariable analysis, molecular group, WHO grade, and extent of resection emerged as independent predictors of recurrence. Among GTR cases, CDKN2A/B homozygous deletion, 1p/6q/10q/14q/18q losses, and 1q gain were significantly associated with shorter RFS. Oncogenic tree modeling and stratified RFS analysis suggested a stepwise accumulation of CNAs, with 22q and 1p losses as early events, and 1q gain and 10q loss as potential late-stage drivers of recurrence. CONCLUSION Molecular classification based on high-risk CNAs and NF2/22q status offers a clinically actionable framework for prognostic stratification in meningiomas. This grouping can be assessed using targeted assays and may enhance WHO grading to inform postoperative monitoring and therapeutic strategies.

  PublisherOA PDFDOI

• Overexpression of plasmalemmal vesicle-associated protein-1 in patient with cyanotic nephropathy: a case report

  BMC Nephrology · 2025-03-03

  articleOpen access

  BACKGROUND: Cyanotic nephropathy (CN) is a known complication of cyanotic congenital heart disease (CCHD). However, many aspects of its pathophysiology remain unclear. CASE PRESENTATION: We report the case of a 29-year-old male with a history of tetralogy of Fallot. Renal biopsy revealed glomerular hypertrophy and focal segmental glomerulosclerosis. Electron microscopy revealed extensive endothelial cell damage. To investigate the etiology of endothelial cell damage, PAL-E staining was conducted, revealing staining along the glomerular capillary wall. CONCLUSION: This is the first report of PAL-E staining in CN, suggesting potential overexpression of PV-1. The association of PV-1 expression with endothelial cell damage indicates its role in the pathogenesis of CN.

  PublisherOA PDFDOI

• Trends in the anatomical location and injury mechanism of pediatric head trauma

  Journal of Neurosurgery Pediatrics · 2025-11-28

  article

  OBJECTIVE: Although pediatric head trauma (PHT) is a critical public health issue, comprehensive research on the anatomical distribution and frequency of impact locations is lacking. The authors aimed to elucidate trends in the mechanisms and anatomical locations of PHT using clinical data across all injury severity levels. METHODS: The medical records of 146 PHT patients aged 0-14 years treated by the authors' neurosurgery department were analyzed, excluding cases of suspected abuse. Clinical data and injury mechanisms were reviewed, and 152 PHTs were assessed to identify the trauma frequencies for 17 different anatomical locations of the head. The authors compared actual to expected PHT hits per region based on area ratios to determine the regions more susceptible to PHT. RESULTS: Most PHTs were minor, without even subcutaneous hematomas. Radiological imaging was performed in 32.2% of patients, revealing abnormalities in 19.2% of those cases. Larger hematomas correlated with these abnormalities, although there was no correlation between vomiting and imaging findings. Notably, 65.7% of the traumas occurred within a horizontal band from the frontal to the occipital region, similar to the area covered by a sports headband. The high injury concentration in this area was particularly focused on the center-forehead region, where susceptibility was significant (p < 0.001). Children younger than 6 years of age had a greater bias toward specific PHT-prone regions. This diminished with age, suggesting changing PHT mechanisms as children mature. CONCLUSIONS: Certain head regions are more prone to accidental PHT, with region-specific susceptibility varying by age. This study can facilitate the design of optimal pediatric head protection and support clinical assessment of injury patterns.

  PublisherDOI

• Thermal mean-field theories

  arXiv (Cornell University) · 2024-07-16

  preprintOpen accessSenior author

  Several closely related ab initio thermal mean-field theories for fermions, both well-established and new ones, are compared with one another at the formalism level and numerically. The theories considered are Fermi-Dirac theory, thermal Hartree-Fock (HF) theory, two modifications of the thermal single-determinant approximation of Kaplan and Argyres, and first-order finite-temperature many-body perturbation theory based on zero-temperature or thermal HF reference. The thermal full-configuration-interaction theory is used as the benchmark.

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• Monte Carlo Explicitly Correlated Second-Order Many-Body Green’s Function Calculations of Semiconductor Band Gaps

  The Journal of Physical Chemistry C · 2024-09-28 · 2 citations

  articleOpen accessSenior authorCorresponding

  A systematically converging series of ab initio, postdensity functional, size-consistent, electron-correlated approximations is desired for predictive computing of electronic band structures of insulating, semiconducting, and metallic solids. A series that meets all of these desiderata (except the applicability to metals) is ab initio many-body Green’s function theory based on Gaussian-type orbital (GTO) basis sets. Here, its leading-order approximation, the second-order Green’s function (GF2) method in the diagonal and frequency-independent approximations with the aug-cc-pVDZ basis set, is applied to the fundamental band gaps of three semiconductors (diamond, silicon, and silicon carbide in the zincblende structure) using cluster models. Corrections are made to the basis set incompleteness errors by the explicit correlation (F12) ansatz (GF2-F12) for the valence band edges. The crystals are modeled as surface-passivated clusters of increasing sizes, whose wave functions are expanded by up to 2709 GTO basis functions. Immense computational costs of these calculations are overcome by the highly scalable stochastic algorithm of the Monte Carlo GF2-F12 method, whose operation cost per state increases only as a cubic power of system size, which has a tiny memory footprint and easily achieves near-perfect parallel efficiency on thousands of CPUs or on hundreds of GPUs. The correlated, F12-corrected highest-occupied and lowest-unoccupied molecular orbital energy (HOMO–LUMO) gap is 5.78 ± 0.07 eV for C87H76 as compared with the experimental value of the fundamental (indirect) band gap of bulk diamond at 5.48 eV. The correlated, F12-corrected HOMO–LUMO gaps for Si75H76 and Si32C43H76 are 2.56 ± 0.15 and 3.50 ± 0.12 eV, respectively, which are expected to decrease further with increasing cluster sizes. The experimental fundamental (indirect) band gaps of bulk silicon and silicon carbide are 1.17 and 2.42 eV, respectively.

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• Thermal quasiparticle theory

  The Journal of Chemical Physics · 2024-12-04 · 1 citations

  articleOpen access1st authorCorresponding

  The widely used thermal Hartree-Fock (HF) theory is generalized to include the effect of electron correlation while maintaining its quasi-independent-particle framework. An electron-correlated internal energy (or grand potential) is postulated in consultation with the second-order finite-temperature many-body perturbation theory (MBPT), which then dictates the corresponding thermal orbital (quasiparticle) energies in such a way that all fundamental thermodynamic relations are obeyed. The associated density matrix is of a one-electron type, whose diagonal elements take the form of the Fermi-Dirac distribution functions, when the grand potential is minimized. The formulas for the entropy and chemical potential are unchanged from those of Fermi-Dirac or thermal HF theory. The theory thus stipulates a finite-temperature extension of the second-order Dyson self-energy of one-particle many-body Green's function theory and can be viewed as a second-order, diagonal, frequency-independent, thermal inverse Dyson equation. At low temperatures, the theory approaches finite-temperature MBPT of the same order, but it may outperform the latter at intermediate temperatures by including additional electron-correlation effects through orbital energies. A physical meaning of these thermal orbital energies is proposed (encompassing that of thermal HF orbital energies, which has been elusive) as a finite-temperature version of Janak's theorem.

  PublisherOA PDFDOI

Recent grants

• CAREER: Quantum Chemistry of Macromolecules

  NSF · $240k · 2009–2011

• SI2-SSE: Adaptive Software for Quantum Chemistry

  NSF · $391k · 2010–2014

• Computational Chemistry of Clusters and Crystals

  NSF · $413k · 2014–2018

• CAREER: Quantum Chemistry of Macromolecules

  NSF · $424k · 2010–2015

Frequent coauthors

• Rodney J. Bartlett

  University of Florida

  30 shared

• Soohaeng Yoo Willow

  Sungkyunkwan University

  26 shared

• Kimihiko Hirao

  Kyoto University

  26 shared

• Kiyoshi Yagi

  RIKEN Center for Computational Science

  25 shared

• Toru Shiozaki

  Simulation Technologies (United States)

  22 shared

• Theresa L. Windus

  22 shared

• Ireneusz Grabowski

  Nicolaus Copernicus University

  22 shared

• Matthew R. Hermes

  University of Chicago

  21 shared

Labs

• Hirata GroupPI

  Not provided

Awards & honors

• Guggenheim Fellow, John Simon Guggenheim Memorial Foundation…
• Frank E. Harris Lecturer, University of Florida, 2020
• Robert S. Mulliken Lecturer, University of Georgia, 2018
• SCS Teaching Award, 2017
• Fellow of the Royal Society of Chemistry, 2015