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All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Proton-Coupled Electron Transfer in a Ruthenium(II) Bipyrimidine Complex in Its Ground and Excited Electronic States

In this work, proton-coupled electron transfer (PCET) was studied for the ground and excited electronic states of a [Ru(terpy)(bpm)(OH 2 )(PF 6 ) 2 ] complex, Ru-bpm. Cyclic voltammetry measurements show that the Ru(II)-aqua moiety undergoes PCET to form a Ru(IV)-oxo moiety in the anodic region, while the bpm ligand undergoes PCET to form bpmH 2 in the cathodic region. The photophysical behavior of Ru-bpm was studied using steady-state and femtosecond transient UV–vis absorption spectroscopy, coupled with density functional theory (DFT) calculations. The lowest-lying excited state of Ru-bpm is described as a (Ru → bpm) metal-to-ligand charge-transfer (MLCT) state, while the metal-centered (MC) excited state was found computationally to be close in energy to the lowest-energy bright MLCT state (MC state was 0.16 eV above the MLCT state). The excited-state kinetics of Ru-bpm were found via transient absorption spectroscopy to be short-lived and were fit well to a biexponential function with lifetimes $τ_1$ = 4 ps and $τ_2$ = 65 ps in aqueous solution. Kinetic isotope effects of 1.75 ($τ_1$) and 1.61 ($τ_2$) were observed for both decay components, indicating that the solvent plays an important role in the excited-state dynamics of Ru-bpm. Based on the pH-dependent studies and the results from prior studies of similar Ru-complexes, we hypothesize that the 3 MLCT state forms an excited-state hydrogen-bond adduct with the solvent molecules and that this process occurs with a 4 ps lifetime. The formation of such a hydrogen-bond complex is consistent with the electronic density accumulation at the peripheral N atoms of the bpm moiety in the 3 MLCT state. The hydrogen-bonded state 3 MLCT decays to the ground state with a 65 ps lifetime. Such a short lifetime is likely associated with the efficient vibrational energy transfer from the 3 MLCT state to the solvent.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

U.S. State Renewables Portfolio & Clean Electricity Standards: 2023 Status Update [Slides]

This report provides an overview and status update on U.S. state renewables portfolio standards (RPS) and has been expanded from previous editions to also cover 100% clean electricity standards (CES) adopted by a growing number of states. The report, published in slide-deck form along with accompanying data files, describes recent legislative revisions, key policy design features, compliance with interim targets, past and projected impacts on clean electricity development, and compliance costs. The 2023 edition presents historical data through year-end 2022 and projections out to 2050. Key trends from this edition of the report include the following: -Evolution of state RPS and CES programs: States continue to refine and revise their RPS policies, often by adopting higher targets and/or broader CES policies. Among the 29 states plus DC with an RPS, 16 states have RPS targets of at least 50% of retail sales, and 17 states have a 100% CES or RPS target. -Historical impacts on renewables development: Roughly half of all growth in U.S. renewable electricity (RE) generation and capacity since 2000 is associated with state RPS requirements, though that percentage has declined in recent years, representing 30% of all U.S. RE capacity additions in 2022. Within some regions, particularly the Northeast and Mid-Atlantic, RPS policies play a more central role in motivating RE growth. -Future RPS and CES demand and incremental needs: RPS and CES policies will require roughly 300 terawatt-hours (TWh) of additional clean electricity supply by 2030 and 800 TWh by 2050, requiring total U.S. non-hydro RE generation to reach 28% of electricity sales by 2050 (compared to 17% today). This amounts to roughly one-quarter of EIA’s projected RE growth through 2050. -RPS target achievement to-date: States have generally met their interim RPS targets in recent years, with only a few exceptions reflecting unique, state-specific issues. Most CES targets are not yet in force. -Renewable energy certificate (REC) pricing trends: Prices for NEPOOL Class I RECs remained at roughly $\$40$ /MWh over the past year, just below alternative compliance payment (ACP) rates in the larger state markets, while PJM Tier I REC prices continued to rise, reaching $\$30$ /MWh by year-end. Prices for solar RECs (or SRECs) remained relatively stable, and continue to exhibit wide variation across states, with the highest prices ($\$200-450$ /MWh) in NJ, MA, and DC. -RPS compliance costs: RPS compliance costs average roughly 3.5% of retail electricity bills across RPS states, though vary widely from state to state, with the highest costs (8-12% of retail bills) in states with solar carve-outs and high SREC prices.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2024

Leveraging State Clean Water Revolving Funds to Expand Clean Energy Financing

To meet clean energy goals, states will need significant capital. Federal funding from the Inflation Reduction Act and the Infrastructure Investment and Jobs Act will help, including by capitalizing clean energy state revolving loan funds (RLFs). States can leverage state clean water revolving funds to finance even more clean energy improvements. New York and Pennsylvania have used this innovative mechanism to extend the impact of their clean energy loan programs. For states looking to extend the reach of their clean energy financing programs, the brief: -Explains how each state leveraged their state revolving funds, -Identifies critical success factors for doing so, and -Offers key elements for replicating this model In New York, New York State Energy Research and Development Authority structured a sale of bonds secured by the repayments from a portfolio of residential energy efficiency loans from its Green Jobs – Green New York Program, with the additional support of a guarantee from the state’s clean water revolving fund. The Pennsylvania Treasury Department received a direct investment of funds from Pennsylvania’s clean water revolving fund to support the relaunch of the Keystone Home Energy Loan Program (HELP), which had previously been shuttered due to lack of support funding. From our review of these two case studies, when facilitating state clean water revolving fund transactions to support clean energy lending, the following critical success factors emerged: -Reference to preventing atmospheric deposition resulting from the combustion of fossil fuels in the state’s Clean Water Act Section 319 Nonpoint Source Pollution Management Plan, which sets out that state’s strategy for reducing pollution into state waterways. -Strong relationships and trust between the clean water revolving fund administrator and the state agency administering the clean energy loan program. -Limited funding exposure for the clean water revolving funds—which are generally large and well capitalized—to ensure that any losses experienced by clean water revolving funds would have a negligible impact on the fund’s ability to support core water and wastewater projects. -Willingness, on the part of the clean water revolving fund administrator, to innovate and engage in careful analysis to support transaction structuring, and support from state energy partner organizations. The brief provides case studies of these states’ experiences, critical success factors, and key elements for replicating the model.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2025

Spin-State and Reorganization Energy Considerations for Metal-Centered Photoredox Catalysis

Transition-metal complexes featuring metal-centered excited states have recently emerged as mechanistically distinct platforms for selective photochemistry, including photoredox catalysis. Among these, Co(III) complexes have demonstrated productive photoinduced electron transfer via the 3 T 1 metal-centered state. In contrast, photoreactivity from the 5 T 2 metal-centered state in Fe(II) polypyridyl complexes remains limited. Building on our prior report concerning reactivity associated with the 5 T 2 state in [Fe(tren(py) 3 )] 2+ (tren(py) 3 = tris(2-pyridylmethyliminoethyl)-amine), we introduced stronger-field ligands in an effort to increase excited-state energies of Fe(II) polypyridyl complexes and enhance reactivity. Despite achieving nanosecond-scale excited-state lifetimes and favorable thermodynamic driving forces, no photoreactivity was observed. Reinvestigation of the observations previously reported for [Fe(tren(py) 3 )] 2+ revealed interactions between the metal complex and the substrate in their respective ground states that mimicked dynamic quenching of the chromophore, prompting a reassessment of mechanistic considerations inherent in leveraging reductive chemistry from the 5 T 2 excited state of Fe(II). Our analysis indicates that electron transfer from the 5 T 2 excited state of a low-spin d6 metal is subject to significant barriers both in terms of reorganization energies and spin conservation that undermines its ability to act as an electron donor for photoredox catalysis. In contrast, ligand fields that are sufficient to stabilize the 3 T 1 excited state have available to them numerous spin-allowed and, in certain cases, near-barrierless pathways to engage in excited-state electron transfer (both oxidative and reductive depending on the identity of the metal). These results highlight the critical role of spin-state changes and their associated reorganization energy requirements in metal-centered photoredox catalysis.

charge transfer↗
DOE OSTI2025

Excited State Covalency, Dynamics, and Photochemistry of Square Planar Ni-Thiolate Complexes Revealed by Ultrafast X-ray Absorption

Highly covalent Ni bis(dithiolene) and related complexes provide an ideal platform for investigating the effects of metal–ligand orbital hybridization on excited state character and dynamics. In particular, we focus on the ligand field excited states that dominate the photophysics of first-row transition metal complexes. Here, we investigate if they can be significantly delocalized off the metal center, possibly yielding photochemical reactivity more similar to charge transfer excited states than metal-centered ligand field excited states. Here [Ni(mpo) 2 ] (mpo = 2-mercaptopyridine- N-oxide) provides a representative example for the larger chemical class and is an active electro- and photo-catalyst for proton reduction. A detailed characterization of the excited state electronic structure, dynamics, and photochemistry of [Ni(mpo) 2 ] is presented based on ultrafast transient X- ray absorption spectroscopy at the Ni and S 1s core absorption K-edges. By comparing the ultrafast Ni K-edge absorption to ab initio calculations, we identify an excited state relaxation mechanism where an initial ligand-to-metal charge transfer excitation results in both excited state electron transfer (generating a catalytically relevant reduced photoproduct [Ni(mpo) 2 ] − ) and relaxation to a pseudo-tetrahedral triplet ligand field excited state. From the ultrafast S K-edge absorption, the ligand field excited state is found to be highly delocalized onto the thiolate ligands and a tetrahedral structural distortion is shown to substantially influence the degree of delocalization. The results identify a significant structural coordinate to target when aiming to control the excited state covalency in square planar complexes.

Lim, Hyeongtaek [SLAC National Accelerator Laborat↗
DOE OSTI2020

Tuning the charge transfer character of the multiexciton state in singlet fission

Intramolecular singlet fission (SF) produces the multiexciton correlated triplet pair state, (T 1 T 1 ), prior to the formation of free triplet excitons. The nature of the multiexciton state is complex, as generation of the (T 1 T 1 ) state may involve a charge transfer (CT) intermediate and has been shown to have both mixed electronic and spin characters. According to transient absorption spectroscopy, a linear terrylene-3,4:11,12-bis(dicarboximide) dimer (TDI 2 ) exhibits solvent-dependent excited-state dynamics. As solvent polarity increases from 1,2,4-trichlorobenzene (ε = 2.2) to chlorobenzene (ε = 5.6) to 1,2-dichlorobenzene (ε = 9.9), the SF rate in TDI2 increases and the multiexciton state, which can be thought of as a linear combination of the 1 (S 1 S 0 ), CT, and (T 1 T 1 ) states, gains more CT character. Eventually, the CT state becomes a trap state as indicated by symmetry-breaking charge separation in TDI2 in pyridine (ε = 12.3). The dielectric environment influences not only the SF rate and the relative contributions of the 1 (S 1 S 0 ), CT, and (T 1 T 1 ) states to the overall multiexciton state but also the rate at which the state mixing evolves, with faster dynamics in higher polarity solvents. More importantly, the tunability and presence of strong CT character in the multiexciton state have implications for SF applications since they often rely on electron transfer from the free triplet excitons. This enhanced CT character in the (T 1 T 1 ) state may assist with two-electron transfer directly from the (T 1 T 1 ) state, allowing for facile extraction of charges in intramolecular SF systems whose (T 1 T 1 ) states do not always efficiently dissociate to two triplet excitons.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Potential State Regulatory Pathways to Facilitate Low-Carbon Fuels

States and the federal government are increasingly engaged in the challenges around decarbonizing the electric grid. In particular, regulators, consumers, stakeholders, and utilities recognize the need to carefully consider the role natural gas will play in a decarbonized future. A variety of technology and policy options to reduce greenhouse gas emissions associated with natural gas use are available, including energy efficiency programs, demand reduction tools, strategic electrification, and strategies to reduce emissions from natural gas production, transportation, and consumption. Low-carbon fuels – mainly renewable natural gas (RNG) and clean hydrogen – are being considered an important component of decarbonization goals. RNG and hydrogen may be able to meaningfully reduce emissions from processes independent of geologic natural gas, displacing emissions of methane, a powerful greenhouse gas. Although RNG and hydrogen are not cost-competitive today with geologic natural gas and are smaller in scale and potential than other decarbonization options, they can be explored as potential critical tools to decarbonize sectors that are difficult to electrify or shift off of natural gas entirely, such as air travel, industrial processes, maritime transport, long-distance trucking, space heating on cold days, and railroads (Nadel, 2022). The role of this report is to provide informational context for state utility regulators to understand the impacts of and challenges associated with broader integration of low-carbon fuels, followed by examples of state regulatory actions taken to date to facilitate the development of low-carbon fuels. Setting clear guidance to calculate the environmental benefits of low-carbon fuels and continuing federal and state investments in research and development to reduce costs relative to fossil fuels will be important steps to take to signal the desire to grow the market for these fuels. State public utility commissions may play a key role in setting regulatory frameworks for low-carbon fuels and ensuring that ratepayer funds, if utilized, are done so to further the public interest. This report is intended to summarize decisions that states have made to date on low-carbon fuels. In the spirit of understanding the current market and sharing information, this report provides success stories, and lessons learned across states as regulators implement varying strategies to achieve decarbonization objectives while maintaining their focus on affordability, safety, and reliability of the energy system. The report begins with an introduction of the role of natural gas in the U.S. economy (Section I) and background information on natural gas use, decarbonization, and low-carbon fuels (Section II). Next, the report describes the current market by discussing the scale of current production, emissions intensity, resource potential, and costs of low-carbon fuels compared to geologic natural gas (Section III). Following these sections, the report describes four strategies states have employed to facilitate low-carbon fuels: opening exploratory dockets, approving voluntary tariffs for customers, approving interconnection tariffs for producers, and considering portfolio-wide procurement targets (Section IV). This section lists states that have taken actions in each category, citing utility filings, commission decisions, stakeholder comments, and other relevant sources. Finally, the report concludes with suggested questions regulators may wish to consider regarding low-carbon fuels, in the interest of preparing to make decisions in the future (Section V). These questions include: Are there existing regulatory or technical barriers to voluntary purchases of low-carbon fuels? Can customers work with utilities to procure low-carbon fuels; are producers able to interconnect projects without significant barriers to entry? Should the infrastructure and/or commodity costs of low-carbon fuels be socialized among all ratepayers, or borne solely by the large commercial and industrial (C&I) customers currently driving the market? Should regulated natural gas and/or electric utilities own and operate low-carbon fuel production? How should regulators consider the unique decarbonization potential of low-carbon fuels, particularly for hard-to-abate sectors, in decision-making? Is additional direction or clarity from state policymakers needed? What no-regrets approaches can help facilitate both near-term RNG development and long-term development of hydrogen and other zero-carbon fuels? We collectively wish to express our gratitude to the U.S. Department of Energy, Office of Fossil Energy and Carbon Management, for supporting this report and other technical assistance resources for state regulators on natural gas topics. State regulators operate under a variety of policy environments, and states have vastly different types of energy resources, infrastructure, and customers. While there is no optimal regulatory, policy, or technological solution that will be successful in every state, state regulators can benefit by exchanging lessons learned with their peers across the country. We look forward to continued engagement with our fellow commissioners, commission staff, NARUC, the U.S. Department of Energy, and other stakeholders to develop sound regulation in the public interest.

03 NATURAL GAS↗
DOE OSTI2026

Many-body entanglement in solid-state emitters

The preparation and control of quantum states lie at the heart of quantum information science. Recent advances in solid-state quantum emitters (QEs) and nanophotonics have transformed the landscape of quantum photonic technologies, enabling scalable generation of quantum states of light and matter. A new frontier in solid-state quantum photonics is the engineering of many-body interactions between QEs and photons to achieve robust coherence and controllable many-body entanglement. These entangled states, including photonic graph and cluster states, superradiant emission and emergent quantum phases, are promising for quantum computation, sensing and simulation. However, intrinsic inhomogeneities and decoherence in solid-state platforms pose considerable challenges in realizing such complex entangled states. This Review provides an overview of fundamental many-body interactions and dynamics at the light–matter interfaces of solid-state QEs and discusses recent advances in mitigating decoherence and harnessing robust many-body coherence.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Quantum mixed state compiling

The task of learning a quantum circuit to prepare a given mixed state is a fundamental quantum subroutine. We present a variational quantum algorithm (VQA) to learn mixed states which is suitable for near-term hardware. Our algorithm represents a generalization of previous VQAs that aimed at learning preparation circuits for pure states. We consider two different ansätze for compiling the target state; the first is based on learning a purification of the state and the second on representing it as a convex combination of pure states. In both cases, the resources required to store and manipulate the compiled state grow with the rank of the approximation. Thus, by learning a lower rank approximation of the target state, our algorithm provides a means of compressing a state for more efficient processing. As a byproduct of our algorithm, one effectively learns the principal components of the target state, and hence our algorithm further provides a new method for principal component analysis. We investigate the efficacy of our algorithm through extensive numerical implementations, showing that typical random states and thermal states of many body systems may be learnt this way. Additionally, we demonstrate on quantum hardware how our algorithm can be used to study hardware noise-induced states.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Challenges for and Pathways Toward Solid-State Batteries

Solid-state batteries utilizing lithium metal anodes have the potential to enable batteries with a specific energy of >500 Wh/kg and an energy density of >1,500 Wh/L for thousands of cycles. When optimized they will improve the energy efficiency, operating temperature range, sustainability, and safety at a lower cost compared to projections for advanced Li-ion batteries. This improved performance is critical for the widespread adoption of electric vehicles and may enable future applications such as electric aviation. Expectations for solid-state batteries are high, there are significant materials and processing challenges that need to be overcome. Some of these challenges are well known; others are more subtle and are just becoming known. The challenges and their solutions must be clearly identified to realize high-energy solid-state Li metal batteries. In the United States, the U.S. Department of Energy (DOE) funds the majority of energy storage research and development, including solid state battery research. Web of Science publication analysis shows that worldwide DOE is second largest funder. Work on solid state batteries is distributed across different arms of DOE and is coordinated at headquarters to ensure a broad national portfolio for advanced batteries, including lithium batteries and solid-state battery devices. We note that university and national laboratory researchers in the US with a long-standing interest in solid state batteries is a small, integrated community with recognized impact for publications, patents and startup companies. The opportunity for this group to engage for research with international colleagues is growing, fostered by periodic bilateral meetings supported by DOE and by the recent joint US German research program for lithium battery interface studies. These are valuable opportunities to speed solid-state battery development. The ORNL led virtual workshop, overviewed here, confirms the community’s shared vision of the exciting advances, opportunities, and challenges. Further, we are seeing that this workshop has spawned several new informal collaborations and draft proposals. This encourages us to propose future discussion. On May 11, 2020, Oak Ridge National Laboratory (ORNL) hosted a 6-hour, on-line national workshop to discuss recent advances and most the prominent obstacles to realizing solid-state Li metal batteries. The workshop included more than 30+ experts from national laboratories, universities, and companies, all of whom have worked on solid-state batteries for multiple years. The participants shared recent advances, many not yet in print, illustrating that the community has gained significant new insights for solid-state Li battery materials over the last 5 years. In this report, the major outcomes of the workshop are organized to identify the gaps in our scientific knowledge for four core materials science areas: (1) Li metal anodes, (2) the solid electrolyte in contact with Li metal, (3) active cathode materials and solid-state composite cathodes, and (4) solid electrolytes. Illustrative examples and discussions are reported with the more comprehensive issues in the report. Discussion of additional challenges related to processing of solid-state battery materials and to the designs and architectures for mechanically robust, long-lived batteries received less attention due to time constraints. These are good themes for deeper discussion at a follow-on workshop, where a complete list of critical research topics can be identified.

25 ENERGY STORAGE↗
DOE OSTI2025

Toward a Balanced Description of Ground and Excited States with Transcorrelated F12 Methods

By correlating only the 1-particle states occupied in the reference determinant, the conventional design for the single-reference R12/F12 explicitly correlated methods biases them toward the ground-state description, thereby making the treatment of response properties of the ground state, and energies and other properties of excited states less robust. While the use of multireference methods and/or extensions of the standard SP-projected geminals can achieve a more balanced description of ground and excited states, here we show that the same goals can be achieved by extending the action of F12 correlators to the occupied and valence unoccupied 1-particle states only. This design choice reflects the strong dependence of the optimal correlation length scale of the F12 ansatz on the orbital energies/structure, and helps to avoid the unphysical raising of the ground-state energy if the F12 geminals are used to correlate pairs of all 1-particle states. The improved F12 geminal design is incorporated into the unitary transcorrelation framework to produce a unitary 2-body Hamiltonian that incorporates the short-range dynamical correlation physics for ground and low-energy excited states in a balanced manner. This explicitly correlated effective Hamiltonian reduces the basis set requirement on the correlation-consistent basis cardinal number by 1 or more over the uncorrelated counterpart for the description of ground-state coupled-cluster singles and doubles (CCSD) energies, vertical excitation energies, and harmonic vibrational frequencies of equation-of-motion CCSD low-energy excited states.

Hamiltonians↗
DOE OSTI2025

Exploring the Coexistence of Spin States in [Fe(tpy-Ph) 2 ] 2+ Complexes on Au(111) Using DFT Calculations

In this work, we systematically study the electronic structure and stability of spin states of the [Fe-(tpy-ph) 2 ] 2+ molecule in both the gas phase and on a Au(111) substrate using density functional theory + U (DFT+ U ) calculations. We find that the stability of the Fe 2+ ion’s spin states predicted by the computations is significantly influenced by the Hubbard U parameter. In the gas phase, the low-spin (LS, S = 0) state is found to be energetically favorable for U (Fe) ≤ 3 eV, whereas the high-spin (HS, S = 2) state is stabilized for U (Fe) > 3 eV. Interaction with the Au(111) substrate is found to elevate the critical U for the spin-state transition to 3.5 eV. Additionally, we perform L-edge X-ray absorption spectroscopy (XAS) calculations for both HS and LS states. The calculated XAS suggests that the HS state more closely aligns with the experimental observations, indicating the potential coexistence of the HS state as the initial state during the X-ray excitation process. These findings enrich our understanding of spin-state dynamics in [Fe(tpy-Ph) 2 ] 2+ .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Time-Resolved X-ray Emission Spectroscopy and Synthetic High-Spin Model Complexes Resolve Ambiguities in Excited-State Assignments of Transition-Metal Chromophores: A Case Study of Fe-Amido Complexes

To fully harness the potential of abundant metal coordination complex photosensitizers, a detailed understanding of the molecular properties that dictate and control the electronic excited-state population dynamics initiated by light absorption is critical. In the absence of detectable luminescence, optical transient absorption (TA) spectroscopy is the most widely employed method for interpreting electron redistribution in such excited states, particularly for those with a charge-transfer character. The assignment of excited-state TA spectral features often relies on spectroelectrochemical measurements, where the transient absorption spectrum generated by a metal-to-ligand charge-transfer (MLCT) electronic excited state, for instance, can be approximated using steady-state spectra generated by electrochemical ligand reduction and metal oxidation and accounting for the loss of absorptions by the electronic ground state. However, the reliability of this approach can be clouded when multiple electronic configurations have similar optical signatures. Using a case study of Fe(II) complexes supported by benzannulated diarylamido ligands, we highlight an example of such an ambiguity and show how time-resolved X-ray emission spectroscopy (XES) measurements can reliably assign excited states from the perspective of the metal, particularly in conjunction with accurate synthetic models of ligand-field electronic excited states, leading to a reinterpretation of the long-lived excited state as a ligand-field metal-centered quintet state. Furthermore, a detailed analysis of the XES data on the long-lived excited state is presented, along with a discussion of the ultrafast dynamics following the photoexcitation of low-spin Fe(II)-N amido complexes using a high-spin ground-state analogue as a spectral model for the 5 T 2 excited state.

14 SOLAR ENERGY↗
DOE OSTI2026

Persistence of collectivity in the low-lying states of 30,31 Na inside the 𝑁 = 20 island of inversion

Near the 𝛽-stability line, nuclei with magic numbers are expected to exhibit spherical ground states. However, mass measurements of neutron-rich nuclei near the 𝑁 = 20 island of inversion have indicated an excess in the binding energies. These results, together with subsequent spectroscopic studies and theoretical works, point to the structural evolution from normal configurations to intruder-deformed configurations characterized by particle-hole excitations across the shell gap. Despite evidence of intruder-dominant ground states for the 30,31 Na isotopes in the vicinity of 𝑁 = 20, a question remains as to whether the deformation persists into the ground-state bands beyond the first excited states. Here, in this work, we report on a heavy-ion inelastic scattering measurement performed with GRETINA, the TRIPLEX device, and the S800 spectrograph to study the low-lying excitations in neutron-rich 30,31 Na . The observed gamma rays for the (4 + ) → (3 + ), (3 + ) → 2$^+_{g.s.}$, and (4 + ) → 2$^+_{g.s.}$ decays in 30 Na and for the (7/2 + ) → (5/2 + ) and (5/2 + )→3/2$^+_{g.s.}$ decays in 31 Na were used to extract the reduced transition probabilities 𝐵⁡(𝐸⁢2↑). We report the first measurement of the 𝐵⁡(𝐸⁢2↑) between the 3/2$^+_{g.s.}$ and the (7/2 + ) states in 31 Na . The results from this study are compared to shell-model calculations, confirming the persistence of large collectivity in the low-lying excited states consistent with the formation of the well-deformed ground-state bands in 30,31 Na .

collective models↗
DOE OSTI2025

Rapid Initial-State Preparation for the Quantum Simulation of Strongly Correlated Molecules

Studies on quantum algorithms for ground-state energy estimation often assume perfect ground-state preparation; however, in reality the initial state will have imperfect overlap with the true ground state. Here, we address that problem in two ways: by faster preparation of matrix-product-state (MPS) approximations and by more efficient filtering of the prepared state to find the ground-state energy. We show how to achieve unitary synthesis with a Toffoli complexity about 7 × lower than that in prior work and use that to derive a more efficient MPS-preparation method. For filtering, we present two different approaches: sampling and binary search. For both, we use the theory of window functions to avoid large phase errors and minimize the complexity. We find that the binary-search approach provides better scaling with the overlap at the cost of a larger constant factor, such that it will be preferred for overlaps less than about 0.003 . Finally, we estimate the total resources to perform ground-state energy estimation of Fe - S cluster systems, including the Fe Mo cofactor by estimating the overlap of different MPS initial states with potential ground states of the Fe Mo cofactor using an extrapolation procedure. With a modest MPS bond dimension of 4000 , our procedure produces an estimate of approximately 0.9 overlap squared with a candidate ground state of the Fe Mo cofactor, producing a total resource estimate of 7.3 × 10 10 Toffoli gates; neglecting the search over candidates and assuming the accuracy of the extrapolation, this validates prior estimates that have used perfect ground-state overlap. This presents an example of a practical path to prepare states of high overlap in a challenging-to-compute chemical system. Published by the American Physical Society 2025

Berry, Dominic W. (ORCID:0000000334461449)↗
DOE OSTI2025

Interplay of superconducting, metallic, and crystalline states of composite fermions at 𝜈 = $\frac{1}{6}$ in wide quantum wells

Evidence for developing fractional quantum Hall effect (FQHE) at filling fraction 𝜈 = 1/6 and 1/8 was recently reported in wide GaAs quantum wells [Wang et al., Phys. Rev. Lett. 134, 046502 (2025)]. In this article, we theoretically investigate the nature of the state at 𝜈 = 1/6 as a function of the quantum well width and the density by considering composite-fermion (CF) crystals, CF Fermi sea, and various kinds of paired CF states. The 𝑓-wave paired state has the lowest energy among the paired CF states. However, for parameters of interest, the energies of the CF crystal, the CF Fermi liquid, and the 𝑓-wave paired CF state are too close to distinguish. We, therefore, predict that 𝑖𝑓 the FQHE at 𝜈 = 1/6 is experimentally confirmed, this state would be an 𝑓-wave paired state of CFs, which can be verified by measurement of its thermal Hall conductance. Exact diagonalization studies on clean systems with up to eight electrons show that the ground states at 𝜈 = 𝑛/(6⁢𝑛 ± 1) are incompressible for all widths and densities we have considered, and are well described by the corresponding Laughlin and Jain states. We propose a phase diagram for large quantum well widths and densities in which at zero disorder, incompressible FQHE states are stabilized at 𝜈 = 𝑛/(6⁢𝑛 ± 1) and 𝜈 = 1/6, but in between these fillings the CF crystal is stabilized. We also present a qualitative discussion on the effects of disorder and propose a schematic phase diagram based on it. With disorder, which creates a spatial variation in the filling factor, two regimes are identified: (i) for small disorder, when the incompressible states percolate at the special fillings, FQHE with quantized Hall plateaus and vanishing longitudinal resistance should occur; and (ii) for larger disorder, when the CF crystal percolates, the longitudinal resistance rises with decreasing temperature but the domains of FQHE liquid produce minima at the special filling factors. Here, experiments are consistent with the latter scenario. We also mention a possible connection of the phase diagram presented here to a puzzling behavior observed for the fractional quantum anomalous Hall effect in pentalayer graphene.

Composite fermions↗
DOE OSTI2025

State-level suicide mortality insights: a comparative study of VHA veterans and the whole US population

Background: Suicide is a leading cause of death in the US Comparative State-level spatial analysis between Veterans Health Administration (VHA veterans) and the whole US population can reveal differences in conditions for targeted interventions and intricate geographical patterns. Methods: The study population contains 2018 and 2019 suicide deaths of VHA veterans and the whole US population. They were used to calculate state-level rates. States were classified by whether their VHA veteran and whole US population rates were above or below respective mean rates. Local Moran’s I was leveraged to examine spatial autocorrelation. Results: State-level suicide mortality rates and disparities among states were generally higher for VHA veterans (2018: 37.3 ± 7.2; 2019: 46.8 ± 8.3) than for the whole US population (2018: 16.6 ± 4.3; 2019: 16.4 ± 4.4). For both populations, there were statistically significant clusters with high suicide rates. Over one-fourth of states demonstrated inverse relationships, with rates above mean for one group but below for other. VHA veterans are at higher risk with over one-third of states had greater than average veteran suicide risk ratio. Conclusions: VHA veterans are at higher risk than the whole population across all states. Mortality disparities among states and clusters of states with high and low rates suggest targeted interventions and cooperative health strategies may help address these differences.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Observation of three-proton-decaying resonant states in 21 Al

The structure of the proton-unbound nucleus 21 Al has been studied via proton transfer from a 9 Be target to a 20 Mg beam at E/A = 103 MeV. Three resonant states in 21 Al are identified by the invariant-mass reconstruction of 18 Ne + 3p events. The decay-energy spectra for the two subsystems of 21 Al , i.e. 18 Ne+ 1 p and 18 Ne+ 2 p , indicate that the observed resonant state with the lowest energy has decay branches consisting of three sequential steps of one-proton decay. Based on the ab initio and the distorted-wave Born approximation (DWBA) calculations, this resonant state at Ε ⁎ = 6.09(11) MeV likely has a spin-parity of (1/2 + - 7/2 + ). Meanwhile, the possibility that the observed resonant peak represents an admixture of several states cannot be ruled out. The good isospin-symmetry of the low-lying states with d 5/2 , d 3/2 configurations in the 21 Al- 21 O pair and the ab initio calculations indicate weak configuration mixing between the s - and d -orbital components. The systematics of experimental energy differences between the 5/2 + ground state and lowest-lying 3/2 + excited state for isotopes (isotones) of Z(N) = 13 suggest a likely semimagic nature of 21 Al.

21Al↗